21353908956 has 12 divisors (see below), whose sum is σ = 49825787592. Its totient is φ = 7117969648.

The previous prime is 21353908931. The next prime is 21353908957. The reversal of 21353908956 is 65980935312.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21353908956² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21353908899 and 21353908908.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21353908957) 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 3 ways as a sum of consecutive naturals, for example, 889746195 + ... + 889746218.

It is an arithmetic number, because the mean of its divisors is an integer number (4152148966).

Almost surely, 2^21353908956 is an apocalyptic number.

It is an amenable number.

21353908956 is an abundant number, since it is smaller than the sum of its proper divisors (28471878636).

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

21353908956 is a wasteful number, since it uses less digits than its factorization.

21353908956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1779492420 (or 1779492418 counting only the distinct ones).

The product of its (nonzero) digits is 1749600, while the sum is 51.

The spelling of 21353908956 in words is "twenty-one billion, three hundred fifty-three million, nine hundred eight thousand, nine hundred fifty-six".