189643681 has 4 divisors (see below), whose sum is σ = 190066500. Its totient is φ = 189220864.

The previous prime is 189643679. The next prime is 189643691. The reversal of 189643681 is 186346981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 186346981 = 347 ⋅537023.

It can be written as a sum of positive squares in 2 ways, for example, as 144216081 + 45427600 = 12009^2 + 6740^2 .

It is a cyclic number.

It is not a de Polignac number, because 189643681 - 2¹ = 189643679 is a prime.

It is a super-2 number, since 2×189643681² = 71929451486459522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (189643621) 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, 210736 + ... + 211633.

It is an arithmetic number, because the mean of its divisors is an integer number (47516625).

Almost surely, 2^189643681 is an apocalyptic number.

It is an amenable number.

189643681 is a deficient number, since it is larger than the sum of its proper divisors (422819).

189643681 is an equidigital number, since it uses as much as digits as its factorization.

189643681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422818.

The product of its digits is 248832, while the sum is 46.

The square root of 189643681 is about 13771.1176380133. The cubic root of 189643681 is about 574.5301073475.

The spelling of 189643681 in words is "one hundred eighty-nine million, six hundred forty-three thousand, six hundred eighty-one".