191631920251 has 2 divisors, whose sum is σ = 191631920252. Its totient is φ = 191631920250.

The previous prime is 191631920239. The next prime is 191631920287. The reversal of 191631920251 is 152029136191.

It is a weak prime.

It is an emirp because it is prime and its reverse (152029136191) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191631920251 is a prime.

It is not a weakly prime, because it can be changed into another prime (191631920231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95815960125 + 95815960126.

It is an arithmetic number, because the mean of its divisors is an integer number (95815960126).

Almost surely, 2^191631920251 is an apocalyptic number.

191631920251 is a deficient number, since it is larger than the sum of its proper divisors (1).

191631920251 is an equidigital number, since it uses as much as digits as its factorization.

191631920251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 29160, while the sum is 40.

The spelling of 191631920251 in words is "one hundred ninety-one billion, six hundred thirty-one million, nine hundred twenty thousand, two hundred fifty-one".