21353365720 has 16 divisors (see below), whose sum is σ = 48045072960. Its totient is φ = 8541346272.

The previous prime is 21353365699. The next prime is 21353365769. The reversal of 21353365720 is 2756335312.

It is a super-2 number, since 2×21353365720² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21353365720.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 266917032 + ... + 266917111.

It is an arithmetic number, because the mean of its divisors is an integer number (3002817060).

Almost surely, 2^21353365720 is an apocalyptic number.

21353365720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21353365720 is an abundant number, since it is smaller than the sum of its proper divisors (26691707240).

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

21353365720 is a wasteful number, since it uses less digits than its factorization.

21353365720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 533834154 (or 533834150 counting only the distinct ones).

The product of its (nonzero) digits is 113400, while the sum is 37.

The spelling of 21353365720 in words is "twenty-one billion, three hundred fifty-three million, three hundred sixty-five thousand, seven hundred twenty".