28111989 has 8 divisors (see below), whose sum is σ = 37756800. Its totient is φ = 18604256.

The previous prime is 28111987. The next prime is 28111997. The reversal of 28111989 is 98911182.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28111989 - 2¹ = 28111987 is a prime.

It is a super-2 number, since 2×28111989² = 1580567851072242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28111987) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33789 + ... + 34610.

It is an arithmetic number, because the mean of its divisors is an integer number (4719600).

Almost surely, 2^28111989 is an apocalyptic number.

It is an amenable number.

28111989 is a deficient number, since it is larger than the sum of its proper divisors (9644811).

28111989 is a wasteful number, since it uses less digits than its factorization.

28111989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68539.

The product of its digits is 10368, while the sum is 39.

The square root of 28111989 is about 5302.0740281516. The cubic root of 28111989 is about 304.0631974164.

The spelling of 28111989 in words is "twenty-eight million, one hundred eleven thousand, nine hundred eighty-nine".