21037507913 has 2 divisors, whose sum is σ = 21037507914. Its totient is φ = 21037507912.

The previous prime is 21037507889. The next prime is 21037507943. The reversal of 21037507913 is 31970573012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19228536889 + 1808971024 = 138667^2 + 42532^2 .

It is a cyclic number.

It is not a de Polignac number, because 21037507913 - 2⁶ = 21037507849 is a prime.

It is not a weakly prime, because it can be changed into another prime (21037507943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10518753956 + 10518753957.

It is an arithmetic number, because the mean of its divisors is an integer number (10518753957).

Almost surely, 2^21037507913 is an apocalyptic number.

It is an amenable number.

21037507913 is a deficient number, since it is larger than the sum of its proper divisors (1).

21037507913 is an equidigital number, since it uses as much as digits as its factorization.

21037507913 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 39690, while the sum is 38.

The spelling of 21037507913 in words is "twenty-one billion, thirty-seven million, five hundred seven thousand, nine hundred thirteen".