189191981 has 8 divisors (see below), whose sum is σ = 207659424. Its totient is φ = 170935920.

The previous prime is 189191957. The next prime is 189191993.

189191981 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-189191981 is a prime.

It is a super-2 number, since 2×189191981² = 71587211349408722, which 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 (189191921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50966 + ... + 54551.

It is an arithmetic number, because the mean of its divisors is an integer number (25957428).

Almost surely, 2^189191981 is an apocalyptic number.

189191981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

189191981 is a deficient number, since it is larger than the sum of its proper divisors (18467443).

189191981 is a wasteful number, since it uses less digits than its factorization.

189191981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105691.

The product of its digits is 46656, while the sum is 47.

The square root of 189191981 is about 13754.7075941294. The cubic root of 189191981 is about 574.0735993636.

The spelling of 189191981 in words is "one hundred eighty-nine million, one hundred ninety-one thousand, nine hundred eighty-one".