189689681 has 2 divisors, whose sum is σ = 189689682. Its totient is φ = 189689680.

The previous prime is 189689653. The next prime is 189689693. The reversal of 189689681 is 186986981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 186595600 + 3094081 = 13660^2 + 1759^2 .

It is a cyclic number.

It is not a de Polignac number, because 189689681 - 2²² = 185495377 is a prime.

It is a super-2 number, since 2×189689681² = 71964350155763522, which contains 22 as substring.

It is a Chen prime.

189689681 is a strobogrammatic number because it is the same when read upside-down.

It is not a weakly prime, because it can be changed into another prime (189689081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94844840 + 94844841.

It is an arithmetic number, because the mean of its divisors is an integer number (94844841).

Almost surely, 2^189689681 is an apocalyptic number.

It is an amenable number.

189689681 is a deficient number, since it is larger than the sum of its proper divisors (1).

189689681 is an equidigital number, since it uses as much as digits as its factorization.

189689681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1492992, while the sum is 56.

The square root of 189689681 is about 13772.7876989374. The cubic root of 189689681 is about 574.5765562954.

The spelling of 189689681 in words is "one hundred eighty-nine million, six hundred eighty-nine thousand, six hundred eighty-one".