21261215052636 has 96 divisors (see below), whose sum is σ = 54731444318208. Its totient is φ = 6382031255040.

The previous prime is 21261215052607. The next prime is 21261215052667. The reversal of 21261215052636 is 63625051216212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 146670985 + ... + 146815871.

It is an arithmetic number, because the mean of its divisors is an integer number (570119211648).

Almost surely, 2^{21261215052636} is an apocalyptic number.

21261215052636 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21261215052636 is an abundant number, since it is smaller than the sum of its proper divisors (33470229265572).

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

21261215052636 is a wasteful number, since it uses less digits than its factorization.

21261215052636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167891 (or 167889 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 42.

Adding to 21261215052636 its reverse (63625051216212), we get a palindrome (84886266268848).

The spelling of 21261215052636 in words is "twenty-one trillion, two hundred sixty-one billion, two hundred fifteen million, fifty-two thousand, six hundred thirty-six".