8642640 has 40 divisors (see below), whose sum is σ = 26792928. Its totient is φ = 2304640.

The previous prime is 8642633. The next prime is 8642651. The reversal of 8642640 is 462468.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 8642598 and 8642607.

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, 17766 + ... + 18245.

Almost surely, 2^8642640 is an apocalyptic number.

8642640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

8642640 is an abundant number, since it is smaller than the sum of its proper divisors (18150288).

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

8642640 is a wasteful number, since it uses less digits than its factorization.

8642640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36027 (or 36021 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The square root of 8642640 is about 2939.8367301604. The cubic root of 8642640 is about 205.2180111789.

The spelling of 8642640 in words is "eight million, six hundred forty-two thousand, six hundred forty".