1231581 has 16 divisors (see below), whose sum is σ = 1846656. Its totient is φ = 724416.

The previous prime is 1231579. The next prime is 1231589. The reversal of 1231581 is 1851321.

It is not a de Polignac number, because 1231581 - 2¹ = 1231579 is a prime.

It is a super-2 number, since 2×1231581² = 3033583519122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231589) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 211 + ... + 1583.

It is an arithmetic number, because the mean of its divisors is an integer number (115416).

2^1231581 is an apocalyptic number.

It is an amenable number.

1231581 is a deficient number, since it is larger than the sum of its proper divisors (615075).

1231581 is a wasteful number, since it uses less digits than its factorization.

1231581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1412.

The product of its digits is 240, while the sum is 21.

The square root of 1231581 is about 1109.7661915917. The cubic root of 1231581 is about 107.1900137817.

The spelling of 1231581 in words is "one million, two hundred thirty-one thousand, five hundred eighty-one".