188138891 has 4 divisors (see below), whose sum is σ = 188854512. Its totient is φ = 187423272.

The previous prime is 188138887. The next prime is 188138897. The reversal of 188138891 is 198831881.

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 188138891 - 2² = 188138887 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (188138897) 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, 357416 + ... + 357941.

It is an arithmetic number, because the mean of its divisors is an integer number (47213628).

Almost surely, 2^188138891 is an apocalyptic number.

188138891 is a deficient number, since it is larger than the sum of its proper divisors (715621).

188138891 is an equidigital number, since it uses as much as digits as its factorization.

188138891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 715620.

The product of its digits is 110592, while the sum is 47.

The square root of 188138891 is about 13716.3730993291. The cubic root of 188138891 is about 573.0064710783.

The spelling of 188138891 in words is "one hundred eighty-eight million, one hundred thirty-eight thousand, eight hundred ninety-one".