28281531 has 8 divisors (see below), whose sum is σ = 37744144. Its totient is φ = 18836640.

The previous prime is 28281511. The next prime is 28281553. The reversal of 28281531 is 13518282.

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

It is not a de Polignac number, because 28281531 - 2⁷ = 28281403 is a prime.

It is a super-2 number, since 2×28281531² = 1599689991407922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28281511) 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, 100 + ... + 7521.

It is an arithmetic number, because the mean of its divisors is an integer number (4718018).

Almost surely, 2^28281531 is an apocalyptic number.

28281531 is a deficient number, since it is larger than the sum of its proper divisors (9462613).

28281531 is a wasteful number, since it uses less digits than its factorization.

28281531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8861.

The product of its digits is 3840, while the sum is 30.

The square root of 28281531 is about 5318.0382661278. The cubic root of 28281531 is about 304.6732359976.

The spelling of 28281531 in words is "twenty-eight million, two hundred eighty-one thousand, five hundred thirty-one".