189971581 has 2 divisors, whose sum is σ = 189971582. Its totient is φ = 189971580.

The previous prime is 189971567. The next prime is 189971597. The reversal of 189971581 is 185179981.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187443481 + 2528100 = 13691^2 + 1590^2 .

It is a cyclic number.

It is not a de Polignac number, because 189971581 - 2¹⁵ = 189938813 is a prime.

It is a super-2 number, since 2×189971581² = 72178403175279122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (189971501) 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 as a sum of consecutive naturals, namely, 94985790 + 94985791.

It is an arithmetic number, because the mean of its divisors is an integer number (94985791).

Almost surely, 2^189971581 is an apocalyptic number.

It is an amenable number.

189971581 is a deficient number, since it is larger than the sum of its proper divisors (1).

189971581 is an equidigital number, since it uses as much as digits as its factorization.

189971581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 49.

The square root of 189971581 is about 13783.0178480622. The cubic root of 189971581 is about 574.8610436748.

The spelling of 189971581 in words is "one hundred eighty-nine million, nine hundred seventy-one thousand, five hundred eighty-one".