123181987 has 4 divisors (see below), whose sum is σ = 123489576. Its totient is φ = 122874400.

The previous prime is 123181967. The next prime is 123182009. The reversal of 123181987 is 789181321.

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

It is a cyclic number.

It is not a de Polignac number, because 123181987 - 2¹⁵ = 123149219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (123181957) 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 3 ways as a sum of consecutive naturals, for example, 153193 + ... + 153994.

It is an arithmetic number, because the mean of its divisors is an integer number (30872394).

Almost surely, 2^123181987 is an apocalyptic number.

123181987 is a deficient number, since it is larger than the sum of its proper divisors (307589).

123181987 is an equidigital number, since it uses as much as digits as its factorization.

123181987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 307588.

The product of its digits is 24192, while the sum is 40.

The square root of 123181987 is about 11098.7380814217. The cubic root of 123181987 is about 497.5641350614.

The spelling of 123181987 in words is "one hundred twenty-three million, one hundred eighty-one thousand, nine hundred eighty-seven".