189991969 has 2 divisors, whose sum is σ = 189991970. Its totient is φ = 189991968.

The previous prime is 189991957. The next prime is 189991973. The reversal of 189991969 is 969199981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 95804944 + 94187025 = 9788^2 + 9705^2 .

It is a cyclic number.

It is not a de Polignac number, because 189991969 - 2⁹ = 189991457 is a prime.

It is a super-2 number, since 2×189991969² = 72193896568993922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (189991979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94995984 + 94995985.

It is an arithmetic number, because the mean of its divisors is an integer number (94995985).

Almost surely, 2^189991969 is an apocalyptic number.

It is an amenable number.

189991969 is a deficient number, since it is larger than the sum of its proper divisors (1).

189991969 is an equidigital number, since it uses as much as digits as its factorization.

189991969 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2834352, while the sum is 61.

The square root of 189991969 is about 13783.7574340236. The cubic root of 189991969 is about 574.8816078869.

The spelling of 189991969 in words is "one hundred eighty-nine million, nine hundred ninety-one thousand, nine hundred sixty-nine".