21394563865 has 32 divisors (see below), whose sum is σ = 26253331200. Its totient is φ = 16734432000.

The previous prime is 21394563809. The next prime is 21394563881. The reversal of 21394563865 is 56836549312.

It is not a de Polignac number, because 21394563865 - 2¹⁵ = 21394531097 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 32366635 + ... + 32367295.

It is an arithmetic number, because the mean of its divisors is an integer number (820416600).

Almost surely, 2^21394563865 is an apocalyptic number.

It is an amenable number.

21394563865 is a deficient number, since it is larger than the sum of its proper divisors (4858767335).

21394563865 is a wasteful number, since it uses less digits than its factorization.

21394563865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1473.

The product of its digits is 4665600, while the sum is 52.

The spelling of 21394563865 in words is "twenty-one billion, three hundred ninety-four million, five hundred sixty-three thousand, eight hundred sixty-five".