640894340 has 24 divisors (see below), whose sum is σ = 1361004120. Its totient is φ = 253476608.

The previous prime is 640894337. The next prime is 640894343. The reversal of 640894340 is 43498046.

It is an interprime number because it is at equal distance from previous prime (640894337) and next prime (640894343).

It can be written as a sum of positive squares in 4 ways, for example, as 59505796 + 581388544 = 7714^2 + 24112^2 .

It is a junction number, because it is equal to n+sod(n) for n = 640894294 and 640894303.

It is not an unprimeable number, because it can be changed into a prime (640894343) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 178247 + ... + 181806.

It is an arithmetic number, because the mean of its divisors is an integer number (56708505).

Almost surely, 2^640894340 is an apocalyptic number.

It is an amenable number.

640894340 is an abundant number, since it is smaller than the sum of its proper divisors (720109780).

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

640894340 is a wasteful number, since it uses less digits than its factorization.

640894340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360151 (or 360149 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 38.

The square root of 640894340 is about 25315.8910568046. The cubic root of 640894340 is about 862.1751052441.

The spelling of 640894340 in words is "six hundred forty million, eight hundred ninety-four thousand, three hundred forty".