21613552605 has 24 divisors (see below), whose sum is σ = 37653676632. Its totient is φ = 11468709504.

The previous prime is 21613552591. The next prime is 21613552607. The reversal of 21613552605 is 50625531612.

21613552605 is a `hidden beast` number, since 2 + 16 + 1 + 35 + 5 + 2 + 605 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 13159301796 + 8454250809 = 114714^2 + 91947^2 .

It is not a de Polignac number, because 21613552605 - 2¹⁰ = 21613551581 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21613552605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21613552607) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1210174 + ... + 1227903.

It is an arithmetic number, because the mean of its divisors is an integer number (1568903193).

Almost surely, 2^21613552605 is an apocalyptic number.

It is an amenable number.

21613552605 is a deficient number, since it is larger than the sum of its proper divisors (16040124027).

21613552605 is a wasteful number, since it uses less digits than its factorization.

21613552605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2438285 (or 2438282 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The spelling of 21613552605 in words is "twenty-one billion, six hundred thirteen million, five hundred fifty-two thousand, six hundred five".