191231994757 has 2 divisors, whose sum is σ = 191231994758. Its totient is φ = 191231994756.

The previous prime is 191231994697. The next prime is 191231994761. The reversal of 191231994757 is 757499132191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 128107442241 + 63124552516 = 357921^2 + 251246^2 .

It is an emirp because it is prime and its reverse (757499132191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 191231994757 - 2¹⁵ = 191231961989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191231994157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95615997378 + 95615997379.

It is an arithmetic number, because the mean of its divisors is an integer number (95615997379).

Almost surely, 2^191231994757 is an apocalyptic number.

It is an amenable number.

191231994757 is a deficient number, since it is larger than the sum of its proper divisors (1).

191231994757 is an equidigital number, since it uses as much as digits as its factorization.

191231994757 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4286520, while the sum is 58.

The spelling of 191231994757 in words is "one hundred ninety-one billion, two hundred thirty-one million, nine hundred ninety-four thousand, seven hundred fifty-seven".