399025421 has 4 divisors (see below), whose sum is σ = 399067644. Its totient is φ = 398983200.

The previous prime is 399025369. The next prime is 399025453. The reversal of 399025421 is 124520993.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 58216900 + 340808521 = 7630^2 + 18461^2 .

It is a cyclic number.

It is not a de Polignac number, because 399025421 - 2⁶ = 399025357 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399025021) 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, 311 + ... + 28251.

It is an arithmetic number, because the mean of its divisors is an integer number (99766911).

Almost surely, 2^399025421 is an apocalyptic number.

It is an amenable number.

399025421 is a deficient number, since it is larger than the sum of its proper divisors (42223).

399025421 is a wasteful number, since it uses less digits than its factorization.

399025421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42222.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 399025421 is about 19975.6206662021. The cubic root of 399025421 is about 736.2074164595.

The spelling of 399025421 in words is "three hundred ninety-nine million, twenty-five thousand, four hundred twenty-one".