21079817984 has 18 divisors (see below), whose sum is σ = 42077293440. Its totient is φ = 10539908864.

The previous prime is 21079817951. The next prime is 21079817987. The reversal of 21079817984 is 48971897012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21079817987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41171264 + ... + 41171775.

Almost surely, 2^21079817984 is an apocalyptic number.

It is an amenable number.

21079817984 is a deficient number, since it is larger than the sum of its proper divisors (20997475456).

21079817984 is an frugal number, since it uses more digits than its factorization.

21079817984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82343055 (or 82343041 counting only the distinct ones).

The product of its (nonzero) digits is 2032128, while the sum is 56.

The spelling of 21079817984 in words is "twenty-one billion, seventy-nine million, eight hundred seventeen thousand, nine hundred eighty-four".