640226440 has 32 divisors (see below), whose sum is σ = 1646297280. Its totient is φ = 219506112.

The previous prime is 640226401. The next prime is 640226467. The reversal of 640226440 is 44622046.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 640226399 and 640226408.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1142982 + ... + 1143541.

It is an arithmetic number, because the mean of its divisors is an integer number (51446790).

Almost surely, 2^640226440 is an apocalyptic number.

It is an amenable number.

640226440 is an abundant number, since it is smaller than the sum of its proper divisors (1006070840).

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

640226440 is a wasteful number, since it uses less digits than its factorization.

640226440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2286541 (or 2286537 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 28.

The square root of 640226440 is about 25302.6962990113. The cubic root of 640226440 is about 861.8754994850.

Adding to 640226440 its reverse (44622046), we get a palindrome (684848486).

The spelling of 640226440 in words is "six hundred forty million, two hundred twenty-six thousand, four hundred forty".