390431681 has 2 divisors, whose sum is σ = 390431682. Its totient is φ = 390431680.

The previous prime is 390431663. The next prime is 390431683. The reversal of 390431681 is 186134093.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 384748225 + 5683456 = 19615^2 + 2384^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-390431681 is a prime.

It is a super-2 number, since 2×390431681² = 304873795056971522, which contains 22 as substring.

Together with 390431683, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (390431683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195215840 + 195215841.

It is an arithmetic number, because the mean of its divisors is an integer number (195215841).

Almost surely, 2^390431681 is an apocalyptic number.

It is an amenable number.

390431681 is a deficient number, since it is larger than the sum of its proper divisors (1).

390431681 is an equidigital number, since it uses as much as digits as its factorization.

390431681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 390431681 is about 19759.3441439740. The cubic root of 390431681 is about 730.8838241083.

The spelling of 390431681 in words is "three hundred ninety million, four hundred thirty-one thousand, six hundred eighty-one".