28185981 has 8 divisors (see below), whose sum is σ = 37611840. Its totient is φ = 18775392.

The previous prime is 28185959. The next prime is 28186009. The reversal of 28185981 is 18958182.

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

It is not a de Polignac number, because 28185981 - 2⁶ = 28185917 is a prime.

It is a super-2 number, since 2×28185981² = 1588899049864722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28185931) 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, 1585 + ... + 7673.

It is an arithmetic number, because the mean of its divisors is an integer number (4701480).

Almost surely, 2^28185981 is an apocalyptic number.

It is an amenable number.

28185981 is a deficient number, since it is larger than the sum of its proper divisors (9425859).

28185981 is a wasteful number, since it uses less digits than its factorization.

28185981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7635.

The product of its digits is 46080, while the sum is 42.

The square root of 28185981 is about 5309.0470896386. The cubic root of 28185981 is about 304.3297329756.

The spelling of 28185981 in words is "twenty-eight million, one hundred eighty-five thousand, nine hundred eighty-one".