21513363021 has 16 divisors (see below), whose sum is σ = 31905993600. Its totient is φ = 14326786944.

The previous prime is 21513363017. The next prime is 21513363049. The reversal of 21513363021 is 12036331512.

21513363021 is a `hidden beast` number, since 2 + 1 + 5 + 1 + 3 + 3 + 630 + 21 = 666.

It is not a de Polignac number, because 21513363021 - 2² = 21513363017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513363071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 403761 + ... + 453926.

It is an arithmetic number, because the mean of its divisors is an integer number (1994124600).

Almost surely, 2^21513363021 is an apocalyptic number.

It is an amenable number.

21513363021 is a deficient number, since it is larger than the sum of its proper divisors (10392630579).

21513363021 is an equidigital number, since it uses as much as digits as its factorization.

21513363021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 858625 (or 858619 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

Adding to 21513363021 its reverse (12036331512), we get a palindrome (33549694533).

The spelling of 21513363021 in words is "twenty-one billion, five hundred thirteen million, three hundred sixty-three thousand, twenty-one".