400321664 has 16 divisors (see below), whose sum is σ = 797516070. Its totient is φ = 200160768.

The previous prime is 400321639. The next prime is 400321703. The reversal of 400321664 is 466123004.

It can be written as a sum of positive squares in only one way, i.e., 400320064 + 1600 = 20008^2 + 40^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1563629 + ... + 1563884.

Almost surely, 2^400321664 is an apocalyptic number.

It is an amenable number.

400321664 is a deficient number, since it is larger than the sum of its proper divisors (397194406).

400321664 is an equidigital number, since it uses as much as digits as its factorization.

400321664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3127527 (or 3127515 counting only the distinct ones).

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

The square root of 400321664 is about 20008.0399839664. The cubic root of 400321664 is about 737.0037501949.

Adding to 400321664 its reverse (466123004), we get a palindrome (866444668).

The spelling of 400321664 in words is "four hundred million, three hundred twenty-one thousand, six hundred sixty-four".