2156581 has 8 divisors (see below), whose sum is σ = 2479104. Its totient is φ = 1837680.

The previous prime is 2156537. The next prime is 2156597. The reversal of 2156581 is 1856512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2156581 - 2¹¹ = 2154533 is a prime.

It is a super-2 number, since 2×2156581² = 9301683219122, 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 (2156521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 531 + ... + 2143.

It is an arithmetic number, because the mean of its divisors is an integer number (309888).

2^2156581 is an apocalyptic number.

It is an amenable number.

2156581 is a deficient number, since it is larger than the sum of its proper divisors (322523).

2156581 is a wasteful number, since it uses less digits than its factorization.

2156581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1811.

The product of its digits is 2400, while the sum is 28.

The square root of 2156581 is about 1468.5302175985. The cubic root of 2156581 is about 129.1978415676.

The spelling of 2156581 in words is "two million, one hundred fifty-six thousand, five hundred eighty-one".