21291802956 has 18 divisors (see below), whose sum is σ = 53820946452. Its totient is φ = 7097267640.

The previous prime is 21291802937. The next prime is 21291802969. The reversal of 21291802956 is 65920819212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-3 number, since 3×21291802956³ (a number of 32 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 295719450 + ... + 295719521.

Almost surely, 2^21291802956 is an apocalyptic number.

It is an amenable number.

21291802956 is an abundant number, since it is smaller than the sum of its proper divisors (32529143496).

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

21291802956 is a wasteful number, since it uses less digits than its factorization.

21291802956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 591438981 (or 591438976 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 45.

The spelling of 21291802956 in words is "twenty-one billion, two hundred ninety-one million, eight hundred two thousand, nine hundred fifty-six".