21807716252 has 12 divisors (see below), whose sum is σ = 43615432560. Its totient is φ = 9346164096.

The previous prime is 21807716251. The next prime is 21807716291. The reversal of 21807716252 is 25261770812.

21807716252 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21807716251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 389423477 + ... + 389423532.

It is an arithmetic number, because the mean of its divisors is an integer number (3634619380).

Almost surely, 2^21807716252 is an apocalyptic number.

It is an amenable number.

21807716252 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21807716252 is a wasteful number, since it uses less digits than its factorization.

21807716252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778847020 (or 778847018 counting only the distinct ones).

The product of its (nonzero) digits is 94080, while the sum is 41.

The spelling of 21807716252 in words is "twenty-one billion, eight hundred seven million, seven hundred sixteen thousand, two hundred fifty-two".