400660640 has 24 divisors (see below), whose sum is σ = 946561140. Its totient is φ = 160264192.

The previous prime is 400660577. The next prime is 400660643. The reversal of 400660640 is 46066004.

It can be written as a sum of positive squares in 2 ways, for example, as 362369296 + 38291344 = 19036^2 + 6188^2 .

It is not an unprimeable number, because it can be changed into a prime (400660643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1251905 + ... + 1252224.

Almost surely, 2^400660640 is an apocalyptic number.

400660640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

400660640 is an abundant number, since it is smaller than the sum of its proper divisors (545900500).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

400660640 is a wasteful number, since it uses less digits than its factorization.

400660640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2504144 (or 2504136 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 400660640 is about 20016.5091861693. The cubic root of 400660640 is about 737.2117130446.

It can be divided in two parts, 4006 and 60640, that added together give a palindrome (64646).

The spelling of 400660640 in words is "four hundred million, six hundred sixty thousand, six hundred forty".