21560645865 has 32 divisors (see below), whose sum is σ = 39613824000. Its totient is φ = 9903453120.

The previous prime is 21560645861. The next prime is 21560645923. The reversal of 21560645865 is 56854606512.

It is not a de Polignac number, because 21560645865 - 2² = 21560645861 is a prime.

It is a super-2 number, since 2×21560645865² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21560645861) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3435565 + ... + 3441834.

It is an arithmetic number, because the mean of its divisors is an integer number (1237932000).

Almost surely, 2^21560645865 is an apocalyptic number.

It is an amenable number.

21560645865 is a deficient number, since it is larger than the sum of its proper divisors (18053178135).

21560645865 is a wasteful number, since it uses less digits than its factorization.

21560645865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6877437.

The product of its (nonzero) digits is 1728000, while the sum is 48.

The spelling of 21560645865 in words is "twenty-one billion, five hundred sixty million, six hundred forty-five thousand, eight hundred sixty-five".