21657605063 has 4 divisors (see below), whose sum is σ = 21880879440. Its totient is φ = 21434330688.

The previous prime is 21657605027. The next prime is 21657605071. The reversal of 21657605063 is 36050675612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21657605063 - 2¹² = 21657600967 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21657605063.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21657605003) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111637043 + ... + 111637236.

It is an arithmetic number, because the mean of its divisors is an integer number (5470219860).

Almost surely, 2^21657605063 is an apocalyptic number.

21657605063 is a deficient number, since it is larger than the sum of its proper divisors (223274377).

21657605063 is an equidigital number, since it uses as much as digits as its factorization.

21657605063 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223274376.

The product of its (nonzero) digits is 226800, while the sum is 41.

The spelling of 21657605063 in words is "twenty-one billion, six hundred fifty-seven million, six hundred five thousand, sixty-three".