28491591 has 16 divisors (see below), whose sum is σ = 39196544. Its totient is φ = 18395424.

The previous prime is 28491577. The next prime is 28491599. The reversal of 28491591 is 19519482.

It is not a de Polignac number, because 28491591 - 2¹⁸ = 28229447 is a prime.

It is a super-2 number, since 2×28491591² = 1623541515422562, 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 (28491599) 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, 30960 + ... + 31866.

It is an arithmetic number, because the mean of its divisors is an integer number (2449784).

Almost surely, 2^28491591 is an apocalyptic number.

28491591 is a deficient number, since it is larger than the sum of its proper divisors (10704953).

28491591 is a wasteful number, since it uses less digits than its factorization.

28491591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1230.

The product of its digits is 25920, while the sum is 39.

The square root of 28491591 is about 5337.7514929041. The cubic root of 28491591 is about 305.4256924197.

The spelling of 28491591 in words is "twenty-eight million, four hundred ninety-one thousand, five hundred ninety-one".