640678946 has 8 divisors (see below), whose sum is σ = 979151004. Its totient is φ = 314295280.

The previous prime is 640678943. The next prime is 640678963. The reversal of 640678946 is 649876046.

It can be written as a sum of positive squares in 2 ways, for example, as 604618921 + 36060025 = 24589^2 + 6005^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 640678894 and 640678903.

It is not an unprimeable number, because it can be changed into a prime (640678943) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3021965 + ... + 3022176.

Almost surely, 2^640678946 is an apocalyptic number.

640678946 is a deficient number, since it is larger than the sum of its proper divisors (338472058).

640678946 is a wasteful number, since it uses less digits than its factorization.

640678946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6044196.

The product of its (nonzero) digits is 1741824, while the sum is 50.

The square root of 640678946 is about 25311.6365729283. The cubic root of 640678946 is about 862.0785068184.

The spelling of 640678946 in words is "six hundred forty million, six hundred seventy-eight thousand, nine hundred forty-six".