21665271567 has 32 divisors (see below), whose sum is σ = 30317068800. Its totient is φ = 13735981952.

The previous prime is 21665271559. The next prime is 21665271581. The reversal of 21665271567 is 76517256612.

It is a cyclic number.

It is not a de Polignac number, because 21665271567 - 2³ = 21665271559 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21665271547) by changing a digit.

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, 12676309 + ... + 12678017.

It is an arithmetic number, because the mean of its divisors is an integer number (947408400).

Almost surely, 2^21665271567 is an apocalyptic number.

21665271567 is a deficient number, since it is larger than the sum of its proper divisors (8651797233).

21665271567 is a wasteful number, since it uses less digits than its factorization.

21665271567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2687.

The product of its digits is 1058400, while the sum is 48.

The spelling of 21665271567 in words is "twenty-one billion, six hundred sixty-five million, two hundred seventy-one thousand, five hundred sixty-seven".