187909491989 has 16 divisors (see below), whose sum is σ = 194083610112. Its totient is φ = 181840122048.

The previous prime is 187909491983. The next prime is 187909492019. The reversal of 187909491989 is 989194909781.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-187909491989 is a prime.

It is a super-2 number, since 2×187909491989² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (187909491983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2635007 + ... + 2705379.

It is an arithmetic number, because the mean of its divisors is an integer number (12130225632).

Almost surely, 2^187909491989 is an apocalyptic number.

It is an amenable number.

187909491989 is a deficient number, since it is larger than the sum of its proper divisors (6174118123).

187909491989 is an equidigital number, since it uses as much as digits as its factorization.

187909491989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71116.

The product of its (nonzero) digits is 105815808, while the sum is 74.

The spelling of 187909491989 in words is "one hundred eighty-seven billion, nine hundred nine million, four hundred ninety-one thousand, nine hundred eighty-nine".