28811391 has 32 divisors (see below), whose sum is σ = 46602240. Its totient is φ = 15466464.

The previous prime is 28811359. The next prime is 28811401. The reversal of 28811391 is 19311882.

It is not a de Polignac number, because 28811391 - 2⁵ = 28811359 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28811191) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 64816 + ... + 65258.

It is an arithmetic number, because the mean of its divisors is an integer number (1456320).

Almost surely, 2^28811391 is an apocalyptic number.

28811391 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

28811391 is a deficient number, since it is larger than the sum of its proper divisors (17790849).

28811391 is a wasteful number, since it uses less digits than its factorization.

28811391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 635.

The product of its digits is 3456, while the sum is 33.

The square root of 28811391 is about 5367.6243348431. The cubic root of 28811391 is about 306.5641798100.

The spelling of 28811391 in words is "twenty-eight million, eight hundred eleven thousand, three hundred ninety-one".