2639640 has 32 divisors (see below), whose sum is σ = 7919280. Its totient is φ = 703872.

The previous prime is 2639639. The next prime is 2639669. The reversal of 2639640 is 469362.

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

It is a junction number, because it is equal to n+sod(n) for n = 2639598 and 2639607.

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, 10879 + ... + 11118.

2^2639640 is an apocalyptic number.

2639640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2639640 is an abundant number, since it is smaller than the sum of its proper divisors (5279640).

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

2639640 is a wasteful number, since it uses less digits than its factorization.

2639640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22011 (or 22007 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 30.

The square root of 2639640 is about 1624.6968948084. The cubic root of 2639640 is about 138.2021821117.

The spelling of 2639640 in words is "two million, six hundred thirty-nine thousand, six hundred forty".