189123721 has 4 divisors (see below), whose sum is σ = 189164052. Its totient is φ = 189083392.

The previous prime is 189123679. The next prime is 189123749. The reversal of 189123721 is 127321981.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 48108096 + 141015625 = 6936^2 + 11875^2 .

It is a cyclic number.

It is not a de Polignac number, because 189123721 - 2⁷ = 189123593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (189123751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12040 + ... + 22873.

It is an arithmetic number, because the mean of its divisors is an integer number (47291013).

Almost surely, 2^189123721 is an apocalyptic number.

It is an amenable number.

189123721 is a deficient number, since it is larger than the sum of its proper divisors (40331).

189123721 is an equidigital number, since it uses as much as digits as its factorization.

189123721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40330.

The product of its digits is 6048, while the sum is 34.

The square root of 189123721 is about 13752.2260379911. The cubic root of 189123721 is about 574.0045496125.

The spelling of 189123721 in words is "one hundred eighty-nine million, one hundred twenty-three thousand, seven hundred twenty-one".