2640690 has 96 divisors (see below), whose sum is σ = 7718256. Its totient is φ = 622080.

The previous prime is 2640689. The next prime is 2640707. The reversal of 2640690 is 960462.

It can be written as a sum of positive squares in 8 ways, for example, as 488601 + 2152089 = 699^2 + 1467^2 .

It is a super-2 number, since 2×2640690² = 13946487352200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 43260 + ... + 43320.

2^2640690 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2640690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3859128).

2640690 is an abundant number, since it is smaller than the sum of its proper divisors (5077566).

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

2640690 is a wasteful number, since it uses less digits than its factorization.

2640690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124 (or 121 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 2640690 is about 1625.0199998769. The cubic root of 2640690 is about 138.2205044403.

The spelling of 2640690 in words is "two million, six hundred forty thousand, six hundred ninety".