400378009 has 4 divisors (see below), whose sum is σ = 400423716. Its totient is φ = 400332304.

The previous prime is 400377977. The next prime is 400378021. The reversal of 400378009 is 900873004.

It is a happy number.

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 232105225 + 168272784 = 15235^2 + 12972^2 .

It is a cyclic number.

It is not a de Polignac number, because 400378009 - 2⁵ = 400377977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (400378109) 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, 5134 + ... + 28759.

It is an arithmetic number, because the mean of its divisors is an integer number (100105929).

Almost surely, 2^400378009 is an apocalyptic number.

It is an amenable number.

400378009 is a deficient number, since it is larger than the sum of its proper divisors (45707).

400378009 is a wasteful number, since it uses less digits than its factorization.

400378009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45706.

The product of its (nonzero) digits is 6048, while the sum is 31.

The square root of 400378009 is about 20009.4479933855. The cubic root of 400378009 is about 737.0383261638.

The spelling of 400378009 in words is "four hundred million, three hundred seventy-eight thousand, nine".