28178491 has 4 divisors (see below), whose sum is σ = 30740184. Its totient is φ = 25616800.

The previous prime is 28178489. The next prime is 28178533. The reversal of 28178491 is 19487182.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 28178491 - 2¹ = 28178489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28178441) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1280830 + ... + 1280851.

It is an arithmetic number, because the mean of its divisors is an integer number (7685046).

Almost surely, 2^28178491 is an apocalyptic number.

28178491 is a deficient number, since it is larger than the sum of its proper divisors (2561693).

28178491 is a wasteful number, since it uses less digits than its factorization.

28178491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2561692.

The product of its digits is 32256, while the sum is 40.

The square root of 28178491 is about 5308.3416431123. The cubic root of 28178491 is about 304.3027735729.

The spelling of 28178491 in words is "twenty-eight million, one hundred seventy-eight thousand, four hundred ninety-one".