2640440 has 64 divisors (see below), whose sum is σ = 6881760. Its totient is φ = 901120.

The previous prime is 2640409. The next prime is 2640497. The reversal of 2640440 is 440462.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7304 + ... + 7656.

2^2640440 is an apocalyptic number.

2640440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2640440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3440880).

2640440 is an abundant number, since it is smaller than the sum of its proper divisors (4241320).

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

2640440 is a wasteful number, since it uses less digits than its factorization.

2640440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 392 (or 388 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 2640440 is about 1624.9430759260. The cubic root of 2640440 is about 138.2161424217.

The spelling of 2640440 in words is "two million, six hundred forty thousand, four hundred forty".