21879537613 has 2 divisors, whose sum is σ = 21879537614. Its totient is φ = 21879537612.

The previous prime is 21879537593. The next prime is 21879537637. The reversal of 21879537613 is 31673597812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21153666249 + 725871364 = 145443^2 + 26942^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21879537613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21879537653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10939768806 + 10939768807.

It is an arithmetic number, because the mean of its divisors is an integer number (10939768807).

Almost surely, 2^21879537613 is an apocalyptic number.

It is an amenable number.

21879537613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21879537613 is an equidigital number, since it uses as much as digits as its factorization.

21879537613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1905120, while the sum is 52.

The spelling of 21879537613 in words is "twenty-one billion, eight hundred seventy-nine million, five hundred thirty-seven thousand, six hundred thirteen".