189717981 has 24 divisors (see below), whose sum is σ = 264810144. Its totient is φ = 120728160.

The previous prime is 189717973. The next prime is 189717989.

It is a happy number.

189717981 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (189717973) and next prime (189717989).

It is not a de Polignac number, because 189717981 - 2³ = 189717973 is a prime.

It is a super-2 number, since 2×189717981² = 71985824629432722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (189717989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 386146 + ... + 386636.

It is an arithmetic number, because the mean of its divisors is an integer number (11033756).

Almost surely, 2^189717981 is an apocalyptic number.

It is an amenable number.

189717981 is a deficient number, since it is larger than the sum of its proper divisors (75092163).

189717981 is an equidigital number, since it uses as much as digits as its factorization.

189717981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 649 (or 590 counting only the distinct ones).

The product of its digits is 254016, while the sum is 51.

The square root of 189717981 is about 13773.8150488527. The cubic root of 189717981 is about 574.6051287651.

The spelling of 189717981 in words is "one hundred eighty-nine million, seven hundred seventeen thousand, nine hundred eighty-one".