28091556 has 96 divisors (see below), whose sum is σ = 78059520. Its totient is φ = 8715168.

The previous prime is 28091551. The next prime is 28091561. The reversal of 28091556 is 65519082.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (28091551) and next prime (28091561).

It is a super-2 number, since 2×28091556² = 1578271037002272, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 28091556.

It is not an unprimeable number, because it can be changed into a prime (28091551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 106681 + ... + 106943.

It is an arithmetic number, because the mean of its divisors is an integer number (813120).

Almost surely, 2^28091556 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28091556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39029760).

28091556 is an abundant number, since it is smaller than the sum of its proper divisors (49967964).

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

28091556 is a wasteful number, since it uses less digits than its factorization.

28091556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342 (or 334 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 28091556 is about 5300.1467904201. The cubic root of 28091556 is about 303.9895108338.

The spelling of 28091556 in words is "twenty-eight million, ninety-one thousand, five hundred fifty-six".