399720877 has 2 divisors, whose sum is σ = 399720878. Its totient is φ = 399720876.

The previous prime is 399720869. The next prime is 399720883. The reversal of 399720877 is 778027993.

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., 397962601 + 1758276 = 19949^2 + 1326^2 .

It is a cyclic number.

It is not a de Polignac number, because 399720877 - 2³ = 399720869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399720857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199860438 + 199860439.

It is an arithmetic number, because the mean of its divisors is an integer number (199860439).

Almost surely, 2^399720877 is an apocalyptic number.

It is an amenable number.

399720877 is a deficient number, since it is larger than the sum of its proper divisors (1).

399720877 is an equidigital number, since it uses as much as digits as its factorization.

399720877 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1333584, while the sum is 52.

The square root of 399720877 is about 19993.0207072368. The cubic root of 399720877 is about 736.6348768612.

The spelling of 399720877 in words is "three hundred ninety-nine million, seven hundred twenty thousand, eight hundred seventy-seven".