21125412636 has 24 divisors (see below), whose sum is σ = 49369307904. Its totient is φ = 7030850160.

The previous prime is 21125412547. The next prime is 21125412653. The reversal of 21125412636 is 63621452112.

It is a junction number, because it is equal to n+sod(n) for n = 21125412597 and 21125412606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1361220 + ... + 1376651.

It is an arithmetic number, because the mean of its divisors is an integer number (2057054496).

Almost surely, 2^21125412636 is an apocalyptic number.

It is an amenable number.

21125412636 is an abundant number, since it is smaller than the sum of its proper divisors (28243895268).

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

21125412636 is a wasteful number, since it uses less digits than its factorization.

21125412636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2738521 (or 2738519 counting only the distinct ones).

The product of its digits is 17280, while the sum is 33.

Adding to 21125412636 its reverse (63621452112), we get a palindrome (84746864748).

The spelling of 21125412636 in words is "twenty-one billion, one hundred twenty-five million, four hundred twelve thousand, six hundred thirty-six".