21621235266605 has 16 divisors (see below), whose sum is σ = 28154580943104. Its totient is φ = 15844569349440.

The previous prime is 21621235266551. The next prime is 21621235266613. The reversal of 21621235266605 is 50666253212612.

It is not a de Polignac number, because 21621235266605 - 2³⁰ = 21620161524781 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 21621235266605.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 1269588389 + ... + 1269605418.

It is an arithmetic number, because the mean of its divisors is an integer number (1759661308944).

Almost surely, 2^{21621235266605} is an apocalyptic number.

It is an amenable number.

21621235266605 is a deficient number, since it is larger than the sum of its proper divisors (6533345676499).

21621235266605 is a wasteful number, since it uses less digits than its factorization.

21621235266605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2539193956.

The product of its (nonzero) digits is 1555200, while the sum is 47.

The spelling of 21621235266605 in words is "twenty-one trillion, six hundred twenty-one billion, two hundred thirty-five million, two hundred sixty-six thousand, six hundred five".