189660721 has 8 divisors (see below), whose sum is σ = 201034440. Its totient is φ = 178311168.

The previous prime is 189660707. The next prime is 189660733. The reversal of 189660721 is 127066981.

It can be written as a sum of positive squares in 4 ways, for example, as 13727025 + 175933696 = 3705^2 + 13264^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 189660721 - 2⁹ = 189660209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (189660701) 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, 11625 + ... + 22681.

It is an arithmetic number, because the mean of its divisors is an integer number (25129305).

Almost surely, 2^189660721 is an apocalyptic number.

It is an amenable number.

189660721 is a deficient number, since it is larger than the sum of its proper divisors (11373719).

189660721 is a wasteful number, since it uses less digits than its factorization.

189660721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12083.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 189660721 is about 13771.7363102842. The cubic root of 189660721 is about 574.5473145292.

The spelling of 189660721 in words is "one hundred eighty-nine million, six hundred sixty thousand, seven hundred twenty-one".