400638638 has 4 divisors (see below), whose sum is σ = 600957960. Its totient is φ = 200319318.

The previous prime is 400638629. The next prime is 400638671. The reversal of 400638638 is 836836004.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×400638638² = 321022636516990088, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100159658 + ... + 100159661.

It is an arithmetic number, because the mean of its divisors is an integer number (150239490).

Almost surely, 2^400638638 is an apocalyptic number.

400638638 is a deficient number, since it is larger than the sum of its proper divisors (200319322).

400638638 is a wasteful number, since it uses less digits than its factorization.

400638638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200319321.

The product of its (nonzero) digits is 82944, while the sum is 38.

The square root of 400638638 is about 20015.9595822933. The cubic root of 400638638 is about 737.1982183083.

The spelling of 400638638 in words is "four hundred million, six hundred thirty-eight thousand, six hundred thirty-eight".