400391805 has 16 divisors (see below), whose sum is σ = 698865984. Its totient is φ = 194129280.

The previous prime is 400391749. The next prime is 400391809. The reversal of 400391805 is 508193004.

It is not a de Polignac number, because 400391805 - 2⁶ = 400391741 is a prime.

It is a super-2 number, since 2×400391805² = 320627195022316050, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400391809) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1213144 + ... + 1213473.

It is an arithmetic number, because the mean of its divisors is an integer number (43679124).

Almost surely, 2^400391805 is an apocalyptic number.

It is an amenable number.

400391805 is a deficient number, since it is larger than the sum of its proper divisors (298474179).

400391805 is a wasteful number, since it uses less digits than its factorization.

400391805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2426636.

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 400391805 is about 20009.7927275622. The cubic root of 400391805 is about 737.0467915505.

The spelling of 400391805 in words is "four hundred million, three hundred ninety-one thousand, eight hundred five".