191303831581 has 2 divisors, whose sum is σ = 191303831582. Its totient is φ = 191303831580.

The previous prime is 191303831569. The next prime is 191303831591. The reversal of 191303831581 is 185138303191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155086316100 + 36217515481 = 393810^2 + 190309^2 .

It is a cyclic number.

It is not a de Polignac number, because 191303831581 - 2⁵ = 191303831549 is a prime.

It is a super-2 number, since 2×191303831581² (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 (191303831501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95651915790 + 95651915791.

It is an arithmetic number, because the mean of its divisors is an integer number (95651915791).

Almost surely, 2^191303831581 is an apocalyptic number.

It is an amenable number.

191303831581 is a deficient number, since it is larger than the sum of its proper divisors (1).

191303831581 is an equidigital number, since it uses as much as digits as its factorization.

191303831581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 43.

The spelling of 191303831581 in words is "one hundred ninety-one billion, three hundred three million, eight hundred thirty-one thousand, five hundred eighty-one".