21720176764 has 72 divisors (see below), whose sum is σ = 45517045392. Its totient is φ = 8988295680.

The previous prime is 21720176761. The next prime is 21720176771. The reversal of 21720176764 is 46767102712.

It is a self number, because there is not a number n which added to its sum of digits gives 21720176764.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21720176761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 522822 + ... + 562834.

It is an arithmetic number, because the mean of its divisors is an integer number (632181186).

Almost surely, 2^21720176764 is an apocalyptic number.

It is an amenable number.

21720176764 is an abundant number, since it is smaller than the sum of its proper divisors (23796868628).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21720176764 is a wasteful number, since it uses less digits than its factorization.

21720176764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40127 (or 40112 counting only the distinct ones).

The product of its (nonzero) digits is 197568, while the sum is 43.

The spelling of 21720176764 in words is "twenty-one billion, seven hundred twenty million, one hundred seventy-six thousand, seven hundred sixty-four".