21665232505 has 64 divisors (see below), whose sum is σ = 32260032000. Its totient is φ = 13636270080.

The previous prime is 21665232461. The next prime is 21665232517. The reversal of 21665232505 is 50523256612.

It is not a de Polignac number, because 21665232505 - 2⁹ = 21665231993 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4059819 + ... + 4065151.

It is an arithmetic number, because the mean of its divisors is an integer number (504063000).

Almost surely, 2^21665232505 is an apocalyptic number.

It is an amenable number.

21665232505 is a deficient number, since it is larger than the sum of its proper divisors (10594799495).

21665232505 is a wasteful number, since it uses less digits than its factorization.

21665232505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5554.

The product of its (nonzero) digits is 108000, while the sum is 37.

The spelling of 21665232505 in words is "twenty-one billion, six hundred sixty-five million, two hundred thirty-two thousand, five hundred five".