61809202591 has 2 divisors, whose sum is σ = 61809202592. Its totient is φ = 61809202590.

The previous prime is 61809202589. The next prime is 61809202601. The reversal of 61809202591 is 19520290816.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 61809202591 - 2¹ = 61809202589 is a prime.

It is a super-2 number, since 2×61809202591² (a number of 22 digits) contains 22 as substring.

Together with 61809202589, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61809202501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30904601295 + 30904601296.

It is an arithmetic number, because the mean of its divisors is an integer number (30904601296).

Almost surely, 2^61809202591 is an apocalyptic number.

61809202591 is a deficient number, since it is larger than the sum of its proper divisors (1).

61809202591 is an equidigital number, since it uses as much as digits as its factorization.

61809202591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 43.

The spelling of 61809202591 in words is "sixty-one billion, eight hundred nine million, two hundred two thousand, five hundred ninety-one".