21390064291 has 2 divisors, whose sum is σ = 21390064292. Its totient is φ = 21390064290.

The previous prime is 21390064279. The next prime is 21390064313. The reversal of 21390064291 is 19246009312.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21390064291 is a prime.

It is a super-2 number, since 2×21390064291² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21390064291.

It is not a weakly prime, because it can be changed into another prime (21390064231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10695032145 + 10695032146.

It is an arithmetic number, because the mean of its divisors is an integer number (10695032146).

Almost surely, 2^21390064291 is an apocalyptic number.

21390064291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21390064291 is an equidigital number, since it uses as much as digits as its factorization.

21390064291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 37.

The spelling of 21390064291 in words is "twenty-one billion, three hundred ninety million, sixty-four thousand, two hundred ninety-one".