400019638 has 4 divisors (see below), whose sum is σ = 600029460. Its totient is φ = 200009818.

The previous prime is 400019603. The next prime is 400019663. The reversal of 400019638 is 836910004.

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

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax 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, 100004908 + ... + 100004911.

It is an arithmetic number, because the mean of its divisors is an integer number (150007365).

Almost surely, 2^400019638 is an apocalyptic number.

400019638 is a deficient number, since it is larger than the sum of its proper divisors (200009822).

400019638 is a wasteful number, since it uses less digits than its factorization.

400019638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200009821.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 400019638 is about 20000.4909439744. The cubic root of 400019638 is about 736.8183573659.

The spelling of 400019638 in words is "four hundred million, nineteen thousand, six hundred thirty-eight".