2640409 has 2 divisors, whose sum is σ = 2640410. Its totient is φ = 2640408.

The previous prime is 2640397. The next prime is 2640497. The reversal of 2640409 is 9040462.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2550409 + 90000 = 1597^2 + 300^2 .

It is a cyclic number.

It is not a de Polignac number, because 2640409 - 2¹⁷ = 2509337 is a prime.

2640409 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (2640509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1320204 + 1320205.

It is an arithmetic number, because the mean of its divisors is an integer number (1320205).

2^2640409 is an apocalyptic number.

It is an amenable number.

2640409 is a deficient number, since it is larger than the sum of its proper divisors (1).

2640409 is an equidigital number, since it uses as much as digits as its factorization.

2640409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 2640409 is about 1624.9335371024. The cubic root of 2640409 is about 138.2156015122.

The spelling of 2640409 in words is "two million, six hundred forty thousand, four hundred nine".