19911608957 has 4 divisors (see below), whose sum is σ = 20163654720. Its totient is φ = 19659563196.

The previous prime is 19911608933. The next prime is 19911608971. The reversal of 19911608957 is 75980611991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19911608957 - 2¹² = 19911604861 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19911608557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126022763 + ... + 126022920.

It is an arithmetic number, because the mean of its divisors is an integer number (5040913680).

Almost surely, 2^19911608957 is an apocalyptic number.

It is an amenable number.

19911608957 is a deficient number, since it is larger than the sum of its proper divisors (252045763).

19911608957 is an equidigital number, since it uses as much as digits as its factorization.

19911608957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252045762.

The product of its (nonzero) digits is 1224720, while the sum is 56.

The spelling of 19911608957 in words is "nineteen billion, nine hundred eleven million, six hundred eight thousand, nine hundred fifty-seven".