399879397 has 4 divisors (see below), whose sum is σ = 400803340. Its totient is φ = 398955456.

The previous prime is 399879391. The next prime is 399879413. The reversal of 399879397 is 793978993.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 793978993 = 79 ⋅10050367.

It can be written as a sum of positive squares in 2 ways, for example, as 175059361 + 224820036 = 13231^2 + 14994^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-399879397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399879391) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 461322 + ... + 462187.

It is an arithmetic number, because the mean of its divisors is an integer number (100200835).

Almost surely, 2^399879397 is an apocalyptic number.

It is an amenable number.

399879397 is a deficient number, since it is larger than the sum of its proper divisors (923943).

399879397 is an equidigital number, since it uses as much as digits as its factorization.

399879397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 923942.

The product of its digits is 23147208, while the sum is 64.

The square root of 399879397 is about 19996.9846976988. The cubic root of 399879397 is about 736.7322414094.

The spelling of 399879397 in words is "three hundred ninety-nine million, eight hundred seventy-nine thousand, three hundred ninety-seven".