81689087 has 2 divisors, whose sum is σ = 81689088. Its totient is φ = 81689086.

The previous prime is 81689071. The next prime is 81689093. The reversal of 81689087 is 78098618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81689087 - 2⁴ = 81689071 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81659087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40844543 + 40844544.

It is an arithmetic number, because the mean of its divisors is an integer number (40844544).

Almost surely, 2^81689087 is an apocalyptic number.

81689087 is a deficient number, since it is larger than the sum of its proper divisors (1).

81689087 is an equidigital number, since it uses as much as digits as its factorization.

81689087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 193536, while the sum is 47.

The square root of 81689087 is about 9038.2015357039. The cubic root of 81689087 is about 433.8983654214.

The spelling of 81689087 in words is "eighty-one million, six hundred eighty-nine thousand, eighty-seven".