2129581 has 4 divisors (see below), whose sum is σ = 2181564. Its totient is φ = 2077600.

The previous prime is 2129579. The next prime is 2129587. The reversal of 2129581 is 1859212.

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 84681 + 2044900 = 291^2 + 1430^2 .

It is a cyclic number.

It is not a de Polignac number, because 2129581 - 2¹ = 2129579 is a prime.

It is a super-2 number, since 2×2129581² = 9070230471122, 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 (2129587) 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, 25930 + ... + 26011.

It is an arithmetic number, because the mean of its divisors is an integer number (545391).

2^2129581 is an apocalyptic number.

It is an amenable number.

2129581 is a deficient number, since it is larger than the sum of its proper divisors (51983).

2129581 is an equidigital number, since it uses as much as digits as its factorization.

2129581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51982.

The product of its digits is 1440, while the sum is 28.

The square root of 2129581 is about 1459.3083978378. The cubic root of 2129581 is about 128.6563978608.

The spelling of 2129581 in words is "two million, one hundred twenty-nine thousand, five hundred eighty-one".