28531531 has 16 divisors (see below), whose sum is σ = 33808320. Its totient is φ = 23569920.

The previous prime is 28531511. The next prime is 28531537. The reversal of 28531531 is 13513582.

It is a cyclic number.

It is not a de Polignac number, because 28531531 - 2¹¹ = 28529483 is a prime.

It is a super-2 number, since 2×28531531² = 1628096522407922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 28531531.

It is not an unprimeable number, because it can be changed into a prime (28531537) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24985 + ... + 26101.

It is an arithmetic number, because the mean of its divisors is an integer number (2113020).

Almost surely, 2^28531531 is an apocalyptic number.

28531531 is a deficient number, since it is larger than the sum of its proper divisors (5276789).

28531531 is a wasteful number, since it uses less digits than its factorization.

28531531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1254.

The product of its digits is 3600, while the sum is 28.

The square root of 28531531 is about 5341.4914583850. The cubic root of 28531531 is about 305.5683427719.

The spelling of 28531531 in words is "twenty-eight million, five hundred thirty-one thousand, five hundred thirty-one".