191657438831 has 2 divisors, whose sum is σ = 191657438832. Its totient is φ = 191657438830.

The previous prime is 191657438801. The next prime is 191657438851. The reversal of 191657438831 is 138834756191.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (138834756191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 191657438831 - 2¹⁸ = 191657176687 is a prime.

It is a super-2 number, since 2×191657438831² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191657438801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95828719415 + 95828719416.

It is an arithmetic number, because the mean of its divisors is an integer number (95828719416).

Almost surely, 2^191657438831 is an apocalyptic number.

191657438831 is a deficient number, since it is larger than the sum of its proper divisors (1).

191657438831 is an equidigital number, since it uses as much as digits as its factorization.

191657438831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4354560, while the sum is 56.

The spelling of 191657438831 in words is "one hundred ninety-one billion, six hundred fifty-seven million, four hundred thirty-eight thousand, eight hundred thirty-one".