188991643 has 4 divisors (see below), whose sum is σ = 189324360. Its totient is φ = 188658928.

The previous prime is 188991641. The next prime is 188991679. The reversal of 188991643 is 346199881.

188991643 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 188991643 - 2¹ = 188991641 is a prime.

It is a super-2 number, since 2×188991643² = 71435682247678898, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (188991641) 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, 165505 + ... + 166642.

It is an arithmetic number, because the mean of its divisors is an integer number (47331090).

Almost surely, 2^188991643 is an apocalyptic number.

188991643 is a deficient number, since it is larger than the sum of its proper divisors (332717).

188991643 is an equidigital number, since it uses as much as digits as its factorization.

188991643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332716.

The product of its digits is 373248, while the sum is 49.

The square root of 188991643 is about 13747.4231403562. The cubic root of 188991643 is about 573.8708963124.

The spelling of 188991643 in words is "one hundred eighty-eight million, nine hundred ninety-one thousand, six hundred forty-three".