7999640 has 32 divisors (see below), whose sum is σ = 19636560. Its totient is φ = 2908800.

The previous prime is 7999637. The next prime is 7999669. The reversal of 7999640 is 469997.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a junction number, because it is equal to n+sod(n) for n = 7999591 and 7999600.

It is a congruent number.

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, 8651 + ... + 9530.

Almost surely, 2^7999640 is an apocalyptic number.

It is an amenable number.

7999640 is an abundant number, since it is smaller than the sum of its proper divisors (11636920).

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

7999640 is a wasteful number, since it uses less digits than its factorization.

7999640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18203 (or 18199 counting only the distinct ones).

The product of its (nonzero) digits is 122472, while the sum is 44.

The square root of 7999640 is about 2828.3634844199. The cubic root of 7999640 is about 199.9969999550.

The spelling of 7999640 in words is "seven million, nine hundred ninety-nine thousand, six hundred forty".