400688640 has 640 divisors, whose sum is σ = 1697034240. Its totient is φ = 88473600.

The previous prime is 400688633. The next prime is 400688641. The reversal of 400688640 is 46886004.

400688640 is a `hidden beast` number, since 4 + 0 + 0 + 6 + 8 + 8 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (640).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 400688595 and 400688604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400688641) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 12925425 + ... + 12925455.

It is an arithmetic number, because the mean of its divisors is an integer number (2651616).

Almost surely, 2^400688640 is an apocalyptic number.

400688640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 400688640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (848517120).

400688640 is an abundant number, since it is smaller than the sum of its proper divisors (1296345600).

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

400688640 is a wasteful number, since it uses less digits than its factorization.

400688640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91 (or 69 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 400688640 is about 20017.2085966051. The cubic root of 400688640 is about 737.2288858879.

The spelling of 400688640 in words is "four hundred million, six hundred eighty-eight thousand, six hundred forty".