189109721 has 2 divisors, whose sum is σ = 189109722. Its totient is φ = 189109720.

The previous prime is 189109693. The next prime is 189109727. The reversal of 189109721 is 127901981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 172003225 + 17106496 = 13115^2 + 4136^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-189109721 is a prime.

It is not a weakly prime, because it can be changed into another prime (189109727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94554860 + 94554861.

It is an arithmetic number, because the mean of its divisors is an integer number (94554861).

Almost surely, 2^189109721 is an apocalyptic number.

It is an amenable number.

189109721 is a deficient number, since it is larger than the sum of its proper divisors (1).

189109721 is an equidigital number, since it uses as much as digits as its factorization.

189109721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 38.

The square root of 189109721 is about 13751.7170200670. The cubic root of 189109721 is about 573.9903855828.

The spelling of 189109721 in words is "one hundred eighty-nine million, one hundred nine thousand, seven hundred twenty-one".