21864355772 has 24 divisors (see below), whose sum is σ = 45629961216. Its totient is φ = 8963027568.

The previous prime is 21864355771. The next prime is 21864355819. The reversal of 21864355772 is 27755346812.

It is a self number, because there is not a number n which added to its sum of digits gives 21864355772.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21864355771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16974788 + ... + 16976075.

It is an arithmetic number, because the mean of its divisors is an integer number (1901248384).

Almost surely, 2^21864355772 is an apocalyptic number.

It is an amenable number.

21864355772 is an abundant number, since it is smaller than the sum of its proper divisors (23765605444).

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

21864355772 is a wasteful number, since it uses less digits than its factorization.

21864355772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33950897 (or 33950895 counting only the distinct ones).

The product of its digits is 2822400, while the sum is 50.

The spelling of 21864355772 in words is "twenty-one billion, eight hundred sixty-four million, three hundred fifty-five thousand, seven hundred seventy-two".