74491961681 has 2 divisors, whose sum is σ = 74491961682. Its totient is φ = 74491961680.

The previous prime is 74491961647. The next prime is 74491961693. The reversal of 74491961681 is 18616919447.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37865657281 + 36626304400 = 194591^2 + 191380^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-74491961681 is a prime.

It is a super-2 number, since 2×74491961681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (74491961881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37245980840 + 37245980841.

It is an arithmetic number, because the mean of its divisors is an integer number (37245980841).

Almost surely, 2^74491961681 is an apocalyptic number.

It is an amenable number.

74491961681 is a deficient number, since it is larger than the sum of its proper divisors (1).

74491961681 is an equidigital number, since it uses as much as digits as its factorization.

74491961681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2612736, while the sum is 56.

The spelling of 74491961681 in words is "seventy-four billion, four hundred ninety-one million, nine hundred sixty-one thousand, six hundred eighty-one".