21063645605 has 16 divisors (see below), whose sum is σ = 25382730240. Its totient is φ = 16780165248.

The previous prime is 21063645563. The next prime is 21063645619. The reversal of 21063645605 is 50654636012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21063645605 - 2²⁴ = 21046868389 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1155401 + ... + 1173489.

It is an arithmetic number, because the mean of its divisors is an integer number (1586420640).

Almost surely, 2^21063645605 is an apocalyptic number.

It is an amenable number.

21063645605 is a deficient number, since it is larger than the sum of its proper divisors (4319084635).

21063645605 is a wasteful number, since it uses less digits than its factorization.

21063645605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19060.

The product of its (nonzero) digits is 129600, while the sum is 38.

The spelling of 21063645605 in words is "twenty-one billion, sixty-three million, six hundred forty-five thousand, six hundred five".