2391581 has 4 divisors (see below), whose sum is σ = 2406972. Its totient is φ = 2376192.

The previous prime is 2391559. The next prime is 2391583. The reversal of 2391581 is 1851932.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 525625 + 1865956 = 725^2 + 1366^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2391581 is a prime.

It is a super-2 number, since 2×2391581² = 11439319359122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2391583) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7460 + ... + 7773.

It is an arithmetic number, because the mean of its divisors is an integer number (601743).

2^2391581 is an apocalyptic number.

It is an amenable number.

2391581 is a deficient number, since it is larger than the sum of its proper divisors (15391).

2391581 is a wasteful number, since it uses less digits than its factorization.

2391581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15390.

The product of its digits is 2160, while the sum is 29.

The square root of 2391581 is about 1546.4737307824. The cubic root of 2391581 is about 133.7298522655.

The spelling of 2391581 in words is "two million, three hundred ninety-one thousand, five hundred eighty-one".