191957581 has 2 divisors, whose sum is σ = 191957582. Its totient is φ = 191957580.

The previous prime is 191957569. The next prime is 191957587. The reversal of 191957581 is 185759191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 116424100 + 75533481 = 10790^2 + 8691^2 .

It is a cyclic number.

It is not a de Polignac number, because 191957581 - 2⁷ = 191957453 is a prime.

It is a super-2 number, since 2×191957581² = 73695425806743122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191957587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95978790 + 95978791.

It is an arithmetic number, because the mean of its divisors is an integer number (95978791).

Almost surely, 2^191957581 is an apocalyptic number.

It is an amenable number.

191957581 is a deficient number, since it is larger than the sum of its proper divisors (1).

191957581 is an equidigital number, since it uses as much as digits as its factorization.

191957581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 113400, while the sum is 46.

The square root of 191957581 is about 13854.8757121816. The cubic root of 191957581 is about 576.8573397268.

The spelling of 191957581 in words is "one hundred ninety-one million, nine hundred fifty-seven thousand, five hundred eighty-one".