400640685 has 16 divisors (see below), whose sum is σ = 643905024. Its totient is φ = 212715072.

The previous prime is 400640663. The next prime is 400640687. The reversal of 400640685 is 586046004.

It is a happy number.

It is not a de Polignac number, because 400640685 - 2¹³ = 400632493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400640687) 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, 56542 + ... + 63231.

It is an arithmetic number, because the mean of its divisors is an integer number (40244064).

Almost surely, 2^400640685 is an apocalyptic number.

It is an amenable number.

400640685 is a deficient number, since it is larger than the sum of its proper divisors (243264339).

400640685 is a wasteful number, since it uses less digits than its factorization.

400640685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120004.

The product of its (nonzero) digits is 23040, while the sum is 33.

The square root of 400640685 is about 20016.0107164240. The cubic root of 400640685 is about 737.1994738389.

Adding to 400640685 its reverse (586046004), we get a palindrome (986686689).

The spelling of 400640685 in words is "four hundred million, six hundred forty thousand, six hundred eighty-five".