399800025 has 81 divisors (see below), whose sum is σ = 757538847. Its totient is φ = 201549600.

The previous prime is 399799997. The next prime is 399800047. The reversal of 399800025 is 520008993.

The square root of 399800025 is 19995.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 143928009 + 255872016 = 11997^2 + 15996^2 .

It is not a de Polignac number, because 399800025 - 2⁹ = 399799513 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 9297654 + ... + 9297696.

Almost surely, 2^399800025 is an apocalyptic number.

399800025 is the 19995-th square number.

399800025 is the 9998-th centered octagonal number.

It is an amenable number.

399800025 is a deficient number, since it is larger than the sum of its proper divisors (357738822).

399800025 is a wasteful number, since it uses less digits than its factorization.

399800025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164 (or 82 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The cubic root of 399800025 is about 736.6834935608.

Multiplying 399800025 by its sum of digits (36), we get a square (14392800900 = 119970²).

The spelling of 399800025 in words is "three hundred ninety-nine million, eight hundred thousand, twenty-five".