191439175981 has 2 divisors, whose sum is σ = 191439175982. Its totient is φ = 191439175980.

The previous prime is 191439175951. The next prime is 191439175987. The reversal of 191439175981 is 189571934191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 131834348100 + 59604827881 = 363090^2 + 244141^2 .

It is a cyclic number.

It is not a de Polignac number, because 191439175981 - 2²⁵ = 191405621549 is a prime.

It is a super-2 number, since 2×191439175981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191439175987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95719587990 + 95719587991.

It is an arithmetic number, because the mean of its divisors is an integer number (95719587991).

Almost surely, 2^191439175981 is an apocalyptic number.

It is an amenable number.

191439175981 is a deficient number, since it is larger than the sum of its proper divisors (1).

191439175981 is an equidigital number, since it uses as much as digits as its factorization.

191439175981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2449440, while the sum is 58.

The spelling of 191439175981 in words is "one hundred ninety-one billion, four hundred thirty-nine million, one hundred seventy-five thousand, nine hundred eighty-one".