189616581 has 24 divisors (see below), whose sum is σ = 341475264. Its totient is φ = 98501760.

The previous prime is 189616579. The next prime is 189616591. The reversal of 189616581 is 185616981.

189616581 is a `hidden beast` number, since 1 + 8 + 9 + 61 + 6 + 581 = 666.

189616581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 189616581 - 2¹ = 189616579 is a prime.

It is a super-2 number, since 2×189616581² = 71908895580259122, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (189616591) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 136116 + ... + 137501.

It is an arithmetic number, because the mean of its divisors is an integer number (14228136).

Almost surely, 2^189616581 is an apocalyptic number.

189616581 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

189616581 is a deficient number, since it is larger than the sum of its proper divisors (151858683).

189616581 is a wasteful number, since it uses less digits than its factorization.

189616581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273641 (or 273638 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 189616581 is about 13770.1336594820. The cubic root of 189616581 is about 574.5027393425.

The spelling of 189616581 in words is "one hundred eighty-nine million, six hundred sixteen thousand, five hundred eighty-one".