28231581 has 16 divisors (see below), whose sum is σ = 43403904. Its totient is φ = 15988224.

The previous prime is 28231561. The next prime is 28231597. The reversal of 28231581 is 18513282.

It is not a de Polignac number, because 28231581 - 2¹³ = 28223389 is a prime.

It is a super-2 number, since 2×28231581² = 1594044331519122, 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 (28231531) 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, 3576 + ... + 8321.

It is an arithmetic number, because the mean of its divisors is an integer number (2712744).

Almost surely, 2^28231581 is an apocalyptic number.

28231581 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28231581 is a deficient number, since it is larger than the sum of its proper divisors (15172323).

28231581 is a wasteful number, since it uses less digits than its factorization.

28231581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12020.

The product of its digits is 3840, while the sum is 30.

The square root of 28231581 is about 5313.3399100754. The cubic root of 28231581 is about 304.4937620223.

The spelling of 28231581 in words is "twenty-eight million, two hundred thirty-one thousand, five hundred eighty-one".