2640581 has 2 divisors, whose sum is σ = 2640582. Its totient is φ = 2640580.

The previous prime is 2640577. The next prime is 2640643. The reversal of 2640581 is 1850462.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1890625 + 749956 = 1375^2 + 866^2 .

It is a cyclic number.

It is not a de Polignac number, because 2640581 - 2² = 2640577 is a prime.

It is a super-2 number, since 2×2640581² = 13945336035122, which contains 22 as substring.

It is a Sophie Germain prime.

It is an Ulam number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2640581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2640511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1320290 + 1320291.

It is an arithmetic number, because the mean of its divisors is an integer number (1320291).

2^2640581 is an apocalyptic number.

It is an amenable number.

2640581 is a deficient number, since it is larger than the sum of its proper divisors (1).

2640581 is an equidigital number, since it uses as much as digits as its factorization.

2640581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 2640581 is about 1624.9864614821. The cubic root of 2640581 is about 138.2186026341.

The spelling of 2640581 in words is "two million, six hundred forty thousand, five hundred eighty-one".