189909981 has 8 divisors (see below), whose sum is σ = 281348160. Its totient is φ = 126606636.

The previous prime is 189909943. The next prime is 189909983.

189909981 is nontrivially palindromic in base 10.

It is a de Polignac number, because none of the positive numbers 2^k-189909981 is a prime.

It is a super-2 number, since 2×189909981² = 72131601766840722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (189909983) 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 7 ways as a sum of consecutive naturals, for example, 3516825 + ... + 3516878.

It is an arithmetic number, because the mean of its divisors is an integer number (35168520).

Almost surely, 2^189909981 is an apocalyptic number.

It is an amenable number.

189909981 is a deficient number, since it is larger than the sum of its proper divisors (91438179).

189909981 is an equidigital number, since it uses as much as digits as its factorization.

189909981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7033712 (or 7033706 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 54.

The square root of 189909981 is about 13780.7830329049. The cubic root of 189909981 is about 574.7989023301.

The spelling of 189909981 in words is "one hundred eighty-nine million, nine hundred nine thousand, nine hundred eighty-one".