21152491812 has 36 divisors (see below), whose sum is σ = 53998202076. Its totient is φ = 6981019200.

The previous prime is 21152491781. The next prime is 21152491813. The reversal of 21152491812 is 21819425112.

21152491812 is a `hidden beast` number, since 2 + 1 + 152 + 491 + 8 + 12 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 14921599716 + 6230892096 = 122154^2 + 78936^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21152491813) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2905123 + ... + 2912394.

Almost surely, 2^21152491812 is an apocalyptic number.

It is an amenable number.

21152491812 is an abundant number, since it is smaller than the sum of its proper divisors (32845710264).

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

21152491812 is a wasteful number, since it uses less digits than its factorization.

21152491812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5817628 (or 5817623 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The spelling of 21152491812 in words is "twenty-one billion, one hundred fifty-two million, four hundred ninety-one thousand, eight hundred twelve".