40391861681 has 2 divisors, whose sum is σ = 40391861682. Its totient is φ = 40391861680.

The previous prime is 40391861663. The next prime is 40391861737. The reversal of 40391861681 is 18616819304.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30610651681 + 9781210000 = 174959^2 + 98900^2 .

It is a cyclic number.

It is not a de Polignac number, because 40391861681 - 2¹⁴ = 40391845297 is a prime.

It is a super-2 number, since 2×40391861681² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (40391861281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20195930840 + 20195930841.

It is an arithmetic number, because the mean of its divisors is an integer number (20195930841).

Almost surely, 2^40391861681 is an apocalyptic number.

It is an amenable number.

40391861681 is a deficient number, since it is larger than the sum of its proper divisors (1).

40391861681 is an equidigital number, since it uses as much as digits as its factorization.

40391861681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 248832, while the sum is 47.

The spelling of 40391861681 in words is "forty billion, three hundred ninety-one million, eight hundred sixty-one thousand, six hundred eighty-one".