21162756864 has 36 divisors (see below), whose sum is σ = 56323797656. Its totient is φ = 7054252032.

The previous prime is 21162756863. The next prime is 21162756869. The reversal of 21162756864 is 46865726112.

It is a super-2 number, since 2×21162756864² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (21162756863) 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, 13777069 + ... + 13778604.

Almost surely, 2^21162756864 is an apocalyptic number.

21162756864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21162756864 is an abundant number, since it is smaller than the sum of its proper divisors (35161040792).

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

21162756864 is an equidigital number, since it uses as much as digits as its factorization.

21162756864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27555692 (or 27555678 counting only the distinct ones).

The product of its digits is 967680, while the sum is 48.

The spelling of 21162756864 in words is "twenty-one billion, one hundred sixty-two million, seven hundred fifty-six thousand, eight hundred sixty-four".