21570373817 has 2 divisors, whose sum is σ = 21570373818. Its totient is φ = 21570373816.

The previous prime is 21570373813. The next prime is 21570373819. The reversal of 21570373817 is 71837307512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11600151616 + 9970222201 = 107704^2 + 99851^2 .

It is a cyclic number.

It is not a de Polignac number, because 21570373817 - 2² = 21570373813 is a prime.

Together with 21570373819, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21570373813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10785186908 + 10785186909.

It is an arithmetic number, because the mean of its divisors is an integer number (10785186909).

Almost surely, 2^21570373817 is an apocalyptic number.

It is an amenable number.

21570373817 is a deficient number, since it is larger than the sum of its proper divisors (1).

21570373817 is an equidigital number, since it uses as much as digits as its factorization.

21570373817 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 246960, while the sum is 44.

The spelling of 21570373817 in words is "twenty-one billion, five hundred seventy million, three hundred seventy-three thousand, eight hundred seventeen".