21056512653 has 16 divisors (see below), whose sum is σ = 34030728000. Its totient is φ = 12761522640.

The previous prime is 21056512651. The next prime is 21056512657. The reversal of 21056512653 is 35621565012.

21056512653 is a `hidden beast` number, since 21 + 0 + 565 + 1 + 26 + 53 = 666.

It is not a de Polignac number, because 21056512653 - 2¹ = 21056512651 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056512651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35448378 + ... + 35448971.

It is an arithmetic number, because the mean of its divisors is an integer number (2126920500).

Almost surely, 2^21056512653 is an apocalyptic number.

It is an amenable number.

21056512653 is a deficient number, since it is larger than the sum of its proper divisors (12974215347).

21056512653 is a wasteful number, since it uses less digits than its factorization.

21056512653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70897369 (or 70897363 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

It can be divided in two parts, 2105651 and 2653, that added together give a square (2108304 = 1452²).

The spelling of 21056512653 in words is "twenty-one billion, fifty-six million, five hundred twelve thousand, six hundred fifty-three".