28881391 has 8 divisors (see below), whose sum is σ = 36008064. Its totient is φ = 22504920.

The previous prime is 28881383. The next prime is 28881397. The reversal of 28881391 is 19318882.

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 28881391 - 2³ = 28881383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28881397) 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, 187465 + ... + 187618.

It is an arithmetic number, because the mean of its divisors is an integer number (4501008).

Almost surely, 2^28881391 is an apocalyptic number.

28881391 is a deficient number, since it is larger than the sum of its proper divisors (7126673).

28881391 is a wasteful number, since it uses less digits than its factorization.

28881391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 375101.

The product of its digits is 27648, while the sum is 40.

The square root of 28881391 is about 5374.1409546085. The cubic root of 28881391 is about 306.8122545700.

The spelling of 28881391 in words is "twenty-eight million, eight hundred eighty-one thousand, three hundred ninety-one".