399790621 has 2 divisors, whose sum is σ = 399790622. Its totient is φ = 399790620.

The previous prime is 399790619. The next prime is 399790637. The reversal of 399790621 is 126097993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 276024996 + 123765625 = 16614^2 + 11125^2 .

It is a cyclic number.

It is not a de Polignac number, because 399790621 - 2¹ = 399790619 is a prime.

Together with 399790619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399790681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199895310 + 199895311.

It is an arithmetic number, because the mean of its divisors is an integer number (199895311).

Almost surely, 2^399790621 is an apocalyptic number.

It is an amenable number.

399790621 is a deficient number, since it is larger than the sum of its proper divisors (1).

399790621 is an equidigital number, since it uses as much as digits as its factorization.

399790621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 183708, while the sum is 46.

The square root of 399790621 is about 19994.7648398274. The cubic root of 399790621 is about 736.6777174849.

The spelling of 399790621 in words is "three hundred ninety-nine million, seven hundred ninety thousand, six hundred twenty-one".