28991808 has 42 divisors (see below), whose sum is σ = 83101434. Its totient is φ = 9663744.

The previous prime is 28991801. The next prime is 28991813. The reversal of 28991808 is 80819982.

It can be written as a sum of positive squares in only one way, i.e., 27373824 + 1617984 = 5232^2 + 1272^2 .

It is a super-2 number, since 2×28991808² = 1681049862217728, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28991801) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 24591 + ... + 25742.

Almost surely, 2^28991808 is an apocalyptic number.

It is an amenable number.

28991808 is an abundant number, since it is smaller than the sum of its proper divisors (54109626).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28991808 is a wasteful number, since it uses less digits than its factorization.

28991808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50351 (or 50338 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 45.

The square root of 28991808 is about 5384.4041453071. The cubic root of 28991808 is about 307.2027506264.

The spelling of 28991808 in words is "twenty-eight million, nine hundred ninety-one thousand, eight hundred eight".