187986989 has 4 divisors (see below), whose sum is σ = 188767260. Its totient is φ = 187206720.

The previous prime is 187986983. The next prime is 187987001. The reversal of 187986989 is 989689781.

187986989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 124657225 + 63329764 = 11165^2 + 7958^2 .

It is a cyclic number.

It is not a de Polignac number, because 187986989 - 2²⁰ = 186938413 is a prime.

It is a super-2 number, since 2×187986989² = 70678216066572242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (187986983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 389774 + ... + 390255.

It is an arithmetic number, because the mean of its divisors is an integer number (47191815).

Almost surely, 2^187986989 is an apocalyptic number.

It is an amenable number.

187986989 is a deficient number, since it is larger than the sum of its proper divisors (780271).

187986989 is an equidigital number, since it uses as much as digits as its factorization.

187986989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 780270.

The product of its digits is 15676416, while the sum is 65.

The square root of 187986989 is about 13710.8347302416. The cubic root of 187986989 is about 572.8522157754.

The spelling of 187986989 in words is "one hundred eighty-seven million, nine hundred eighty-six thousand, nine hundred eighty-nine".