394659721 has 2 divisors, whose sum is σ = 394659722. Its totient is φ = 394659720.

The previous prime is 394659653. The next prime is 394659787. The reversal of 394659721 is 127956493.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 394578496 + 81225 = 19864^2 + 285^2 .

It is a cyclic number.

It is not a de Polignac number, because 394659721 - 2⁷ = 394659593 is a prime.

It is not a weakly prime, because it can be changed into another prime (394654721) 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, 197329860 + 197329861.

It is an arithmetic number, because the mean of its divisors is an integer number (197329861).

Almost surely, 2^394659721 is an apocalyptic number.

It is an amenable number.

394659721 is a deficient number, since it is larger than the sum of its proper divisors (1).

394659721 is an equidigital number, since it uses as much as digits as its factorization.

394659721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 408240, while the sum is 46.

The square root of 394659721 is about 19866.0444225820. The cubic root of 394659721 is about 733.5126390519.

The spelling of 394659721 in words is "three hundred ninety-four million, six hundred fifty-nine thousand, seven hundred twenty-one".