28931661 has 40 divisors (see below), whose sum is σ = 49658400. Its totient is φ = 16601760.

The previous prime is 28931659. The next prime is 28931663. The reversal of 28931661 is 16613982.

28931661 is a `hidden beast` number, since 289 + 316 + 61 = 666.

It is an interprime number because it is at equal distance from previous prime (28931659) and next prime (28931663).

It is not a de Polignac number, because 28931661 - 2¹ = 28931659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28931663) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 16075 + ... + 17783.

It is an arithmetic number, because the mean of its divisors is an integer number (1241460).

Almost surely, 2^28931661 is an apocalyptic number.

It is an amenable number.

28931661 is a deficient number, since it is larger than the sum of its proper divisors (20726739).

28931661 is a wasteful number, since it uses less digits than its factorization.

28931661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1751 (or 1742 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 28931661 is about 5378.8159477714. The cubic root of 28931661 is about 306.9901604998.

It can be divided in two parts, 28931 and 661, that added together give a palindrome (29592).

The spelling of 28931661 in words is "twenty-eight million, nine hundred thirty-one thousand, six hundred sixty-one".