400640402 has 4 divisors (see below), whose sum is σ = 600960606. Its totient is φ = 200320200.

The previous prime is 400640399. The next prime is 400640407. The reversal of 400640402 is 204046004.

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

It can be written as a sum of positive squares in only one way, i.e., 331567681 + 69072721 = 18209^2 + 8311^2 .

It is not an unprimeable number, because it can be changed into a prime (400640407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100160099 + ... + 100160102.

Almost surely, 2^400640402 is an apocalyptic number.

400640402 is a deficient number, since it is larger than the sum of its proper divisors (200320204).

400640402 is a wasteful number, since it uses less digits than its factorization.

400640402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200320203.

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 400640402 is about 20016.0036470820. The cubic root of 400640402 is about 737.1993002607.

Adding to 400640402 its reverse (204046004), we get a palindrome (604686406).

The spelling of 400640402 in words is "four hundred million, six hundred forty thousand, four hundred two".