640120340 has 12 divisors (see below), whose sum is σ = 1344252756. Its totient is φ = 256048128.

The previous prime is 640120339. The next prime is 640120361. The reversal of 640120340 is 43021046.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 76247824 + 563872516 = 8732^2 + 23746^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 32006017 = 640120340 / (6 + 4 + 0 + 1 + 2 + 0 + 3 + 4 + 0).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16002989 + ... + 16003028.

It is an arithmetic number, because the mean of its divisors is an integer number (112021063).

Almost surely, 2^640120340 is an apocalyptic number.

It is an amenable number.

640120340 is an abundant number, since it is smaller than the sum of its proper divisors (704132416).

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

640120340 is a wasteful number, since it uses less digits than its factorization.

640120340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32006026 (or 32006024 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 640120340 is about 25300.5995976380. The cubic root of 640120340 is about 861.8278861007.

Adding to 640120340 its reverse (43021046), we get a palindrome (683141386).

The spelling of 640120340 in words is "six hundred forty million, one hundred twenty thousand, three hundred forty".