400739681 has 2 divisors, whose sum is σ = 400739682. Its totient is φ = 400739680.

The previous prime is 400739639. The next prime is 400739693. The reversal of 400739681 is 186937004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 391406656 + 9333025 = 19784^2 + 3055^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400739681 is a prime.

It is a super-2 number, since 2×400739681² = 321184583855963522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (400733681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200369840 + 200369841.

It is an arithmetic number, because the mean of its divisors is an integer number (200369841).

Almost surely, 2^400739681 is an apocalyptic number.

It is an amenable number.

400739681 is a deficient number, since it is larger than the sum of its proper divisors (1).

400739681 is an equidigital number, since it uses as much as digits as its factorization.

400739681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 400739681 is about 20018.4834840205. The cubic root of 400739681 is about 737.2601880829.

The spelling of 400739681 in words is "four hundred million, seven hundred thirty-nine thousand, six hundred eighty-one".