21172752678 has 64 divisors (see below), whose sum is σ = 53582450688. Its totient is φ = 5417327520.

The previous prime is 21172752673. The next prime is 21172752691. The reversal of 21172752678 is 87625727112.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21172752673) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 311050 + ... + 372957.

It is an arithmetic number, because the mean of its divisors is an integer number (837225792).

Almost surely, 2^21172752678 is an apocalyptic number.

21172752678 is an abundant number, since it is smaller than the sum of its proper divisors (32409698010).

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

21172752678 is a wasteful number, since it uses less digits than its factorization.

21172752678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 684097.

The product of its digits is 658560, while the sum is 48.

The spelling of 21172752678 in words is "twenty-one billion, one hundred seventy-two million, seven hundred fifty-two thousand, six hundred seventy-eight".