187908989 has 2 divisors, whose sum is σ = 187908990. Its totient is φ = 187908988.

The previous prime is 187908983. The next prime is 187908991. The reversal of 187908989 is 989809781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 164916964 + 22992025 = 12842^2 + 4795^2 .

It is an emirp because it is prime and its reverse (989809781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 187908989 - 2⁸ = 187908733 is a prime.

Together with 187908991, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (187908983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 93954494 + 93954495.

It is an arithmetic number, because the mean of its divisors is an integer number (93954495).

Almost surely, 2^187908989 is an apocalyptic number.

It is an amenable number.

187908989 is a deficient number, since it is larger than the sum of its proper divisors (1).

187908989 is an equidigital number, since it uses as much as digits as its factorization.

187908989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2612736, while the sum is 59.

The square root of 187908989 is about 13707.9899693573. The cubic root of 187908989 is about 572.7729750889.

The spelling of 187908989 in words is "one hundred eighty-seven million, nine hundred eight thousand, nine hundred eighty-nine".