399757849 has 2 divisors, whose sum is σ = 399757850. Its totient is φ = 399757848.

The previous prime is 399757823. The next prime is 399757859. The reversal of 399757849 is 948757993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 215884249 + 183873600 = 14693^2 + 13560^2 .

It is an emirp because it is prime and its reverse (948757993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 399757849 - 2¹⁹ = 399233561 is a prime.

It is not a weakly prime, because it can be changed into another prime (399757819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199878924 + 199878925.

It is an arithmetic number, because the mean of its divisors is an integer number (199878925).

Almost surely, 2^399757849 is an apocalyptic number.

It is an amenable number.

399757849 is a deficient number, since it is larger than the sum of its proper divisors (1).

399757849 is an equidigital number, since it uses as much as digits as its factorization.

399757849 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17146080, while the sum is 61.

The square root of 399757849 is about 19993.9453085178. The cubic root of 399757849 is about 736.6575877298.

It can be divided in two parts, 39975 and 7849, that multiplied together give a triangular number (313763775 = T₂₅₀₅₀).

The spelling of 399757849 in words is "three hundred ninety-nine million, seven hundred fifty-seven thousand, eight hundred forty-nine".