21655610413 has 4 divisors (see below), whose sum is σ = 21813680700. Its totient is φ = 21497540128.

The previous prime is 21655610407. The next prime is 21655610441. The reversal of 21655610413 is 31401655612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11083246729 + 10572363684 = 105277^2 + 102822^2 .

It is a cyclic number.

It is not a de Polignac number, because 21655610413 - 2²⁵ = 21622055981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21655610213) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79034938 + ... + 79035211.

It is an arithmetic number, because the mean of its divisors is an integer number (5453420175).

Almost surely, 2^21655610413 is an apocalyptic number.

It is an amenable number.

21655610413 is a deficient number, since it is larger than the sum of its proper divisors (158070287).

21655610413 is a wasteful number, since it uses less digits than its factorization.

21655610413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158070286.

The product of its (nonzero) digits is 21600, while the sum is 34.

The spelling of 21655610413 in words is "twenty-one billion, six hundred fifty-five million, six hundred ten thousand, four hundred thirteen".