21613031613 has 6 divisors (see below), whose sum is σ = 31218823454. Its totient is φ = 14408687736.

The previous prime is 21613031599. The next prime is 21613031681. The reversal of 21613031613 is 31613031612.

21613031613 is a `hidden beast` number, since 2 + 1 + 6 + 13 + 0 + 31 + 613 = 666.

It can be written as a sum of positive squares in only one way, i.e., 11689285689 + 9923745924 = 108117^2 + 99618^2 .

It is not a de Polignac number, because 21613031613 - 2¹² = 21613027517 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 (21613031683) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1200723970 + ... + 1200723987.

Almost surely, 2^21613031613 is an apocalyptic number.

It is an amenable number.

21613031613 is a deficient number, since it is larger than the sum of its proper divisors (9605791841).

21613031613 is a wasteful number, since it uses less digits than its factorization.

21613031613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2401447963 (or 2401447960 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

Subtracting 21613031613 from its reverse (31613031612), we obtain a palindrome (9999999999).

The spelling of 21613031613 in words is "twenty-one billion, six hundred thirteen million, thirty-one thousand, six hundred thirteen".