640979340 has 48 divisors (see below), whose sum is σ = 1795895808. Its totient is φ = 170817984.

The previous prime is 640979329. The next prime is 640979351. The reversal of 640979340 is 43979046.

It is an interprime number because it is at equal distance from previous prime (640979329) and next prime (640979351).

It is a junction number, because it is equal to n+sod(n) for n = 640979292 and 640979301.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 140739 + ... + 145221.

It is an arithmetic number, because the mean of its divisors is an integer number (37414496).

Almost surely, 2^640979340 is an apocalyptic number.

640979340 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

640979340 is an abundant number, since it is smaller than the sum of its proper divisors (1154916468).

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

640979340 is a wasteful number, since it uses less digits than its factorization.

640979340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6878 (or 6876 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 42.

The square root of 640979340 is about 25317.5697885875. The cubic root of 640979340 is about 862.2132195061.

It can be divided in two parts, 64097 and 9340, that added together give a palindrome (73437).

The spelling of 640979340 in words is "six hundred forty million, nine hundred seventy-nine thousand, three hundred forty".