21001202591 has 2 divisors, whose sum is σ = 21001202592. Its totient is φ = 21001202590.

The previous prime is 21001202587. The next prime is 21001202609. The reversal of 21001202591 is 19520210012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21001202591 - 2² = 21001202587 is a prime.

It is a super-2 number, since 2×21001202591² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001202561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500601295 + 10500601296.

It is an arithmetic number, because the mean of its divisors is an integer number (10500601296).

Almost surely, 2^21001202591 is an apocalyptic number.

21001202591 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001202591 is an equidigital number, since it uses as much as digits as its factorization.

21001202591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 23.

The spelling of 21001202591 in words is "twenty-one billion, one million, two hundred two thousand, five hundred ninety-one".