187388989 has 2 divisors, whose sum is σ = 187388990. Its totient is φ = 187388988.

The previous prime is 187388987. The next prime is 187389023. The reversal of 187388989 is 989883781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 160452889 + 26936100 = 12667^2 + 5190^2 .

It is an emirp because it is prime and its reverse (989883781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 187388989 - 2¹ = 187388987 is a prime.

It is a super-2 number, since 2×187388989² = 70229266396884242, which contains 22 as substring.

Together with 187388987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (187388987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 93694494 + 93694495.

It is an arithmetic number, because the mean of its divisors is an integer number (93694495).

Almost surely, 2^187388989 is an apocalyptic number.

It is an amenable number.

187388989 is a deficient number, since it is larger than the sum of its proper divisors (1).

187388989 is an equidigital number, since it uses as much as digits as its factorization.

187388989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6967296, while the sum is 61.

The square root of 187388989 is about 13689.0097888781. The cubic root of 187388989 is about 572.2441426457.

The spelling of 187388989 in words is "one hundred eighty-seven million, three hundred eighty-eight thousand, nine hundred eighty-nine".