public BigInteger toBigInteger() {
        return new BigInteger(toString());
    }
Get this number as a {@link BigInteger}. This is a convenience method for
calling <code>new BigInteger(toString())</code>
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-microsoft-module/src/main/java/org/apache/tika/parser/microsoft/onenote/fsshttpb/unsigned/UNumber.java