191231994697 has 2 divisors, whose sum is σ = 191231994698. Its totient is φ = 191231994696.

The previous prime is 191231994659. The next prime is 191231994757. The reversal of 191231994697 is 796499132191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 181677127696 + 9554867001 = 426236^2 + 97749^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191231994697 is a prime.

It is a super-2 number, since 2×191231994697² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (191231994647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95615997348 + 95615997349.

It is an arithmetic number, because the mean of its divisors is an integer number (95615997349).

Almost surely, 2^191231994697 is an apocalyptic number.

It is an amenable number.

191231994697 is a deficient number, since it is larger than the sum of its proper divisors (1).

191231994697 is an equidigital number, since it uses as much as digits as its factorization.

191231994697 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6613488, while the sum is 61.

The spelling of 191231994697 in words is "one hundred ninety-one billion, two hundred thirty-one million, nine hundred ninety-four thousand, six hundred ninety-seven".