21621415563506 has 16 divisors (see below), whose sum is σ = 36600515375040. Its totient is φ = 9489022504080.

The previous prime is 21621415563467. The next prime is 21621415563523. The reversal of 21621415563506 is 60536551412612.

It is a happy number.

It is a super-2 number, since 2×21621415563506² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16944682406 + ... + 16944683681.

It is an arithmetic number, because the mean of its divisors is an integer number (2287532210940).

Almost surely, 2^{21621415563506} is an apocalyptic number.

21621415563506 is a deficient number, since it is larger than the sum of its proper divisors (14979099811534).

21621415563506 is a wasteful number, since it uses less digits than its factorization.

21621415563506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33889366129.

The product of its (nonzero) digits is 1296000, while the sum is 47.

The spelling of 21621415563506 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred fifteen million, five hundred sixty-three thousand, five hundred six".