189619681 has 2 divisors, whose sum is σ = 189619682. Its totient is φ = 189619680.

The previous prime is 189619679. The next prime is 189619697. The reversal of 189619681 is 186916981.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 163609681 + 26010000 = 12791^2 + 5100^2 .

It is a cyclic number.

It is not a de Polignac number, because 189619681 - 2¹ = 189619679 is a prime.

It is a super-2 number, since 2×189619681² = 71911246845083522, which contains 22 as substring.

Together with 189619679, it forms a pair of twin primes.

189619681 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 (189619621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94809840 + 94809841.

It is an arithmetic number, because the mean of its divisors is an integer number (94809841).

Almost surely, 2^189619681 is an apocalyptic number.

It is an amenable number.

189619681 is a deficient number, since it is larger than the sum of its proper divisors (1).

189619681 is an equidigital number, since it uses as much as digits as its factorization.

189619681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 186624, while the sum is 49.

The square root of 189619681 is about 13770.2462214733. The cubic root of 189619681 is about 574.5058701320.

The spelling of 189619681 in words is "one hundred eighty-nine million, six hundred nineteen thousand, six hundred eighty-one".