399400069 has 2 divisors, whose sum is σ = 399400070. Its totient is φ = 399400068.

The previous prime is 399400021. The next prime is 399400097. The reversal of 399400069 is 960004993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 386712225 + 12687844 = 19665^2 + 3562^2 .

It is a cyclic number.

It is not a de Polignac number, because 399400069 - 2¹³ = 399391877 is a prime.

It is a super-2 number, since 2×399400069² = 319040830234409522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399400019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199700034 + 199700035.

It is an arithmetic number, because the mean of its divisors is an integer number (199700035).

Almost surely, 2^399400069 is an apocalyptic number.

It is an amenable number.

399400069 is a deficient number, since it is larger than the sum of its proper divisors (1).

399400069 is an equidigital number, since it uses as much as digits as its factorization.

399400069 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52488, while the sum is 40.

The square root of 399400069 is about 19984.9960970724. The cubic root of 399400069 is about 736.4377546318.

The spelling of 399400069 in words is "three hundred ninety-nine million, four hundred thousand, sixty-nine".