81689177 has 2 divisors, whose sum is σ = 81689178. Its totient is φ = 81689176.

The previous prime is 81689173. The next prime is 81689183. The reversal of 81689177 is 77198618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67634176 + 14055001 = 8224^2 + 3749^2 .

It is a cyclic number.

It is not a de Polignac number, because 81689177 - 2² = 81689173 is a prime.

It is not a weakly prime, because it can be changed into another prime (81689171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40844588 + 40844589.

It is an arithmetic number, because the mean of its divisors is an integer number (40844589).

Almost surely, 2^81689177 is an apocalyptic number.

It is an amenable number.

81689177 is a deficient number, since it is larger than the sum of its proper divisors (1).

81689177 is an equidigital number, since it uses as much as digits as its factorization.

81689177 is an evil number, because the sum of its binary digits is even.

The product of its digits is 169344, while the sum is 47.

The square root of 81689177 is about 9038.2065145691. The cubic root of 81689177 is about 433.8985247688.

The spelling of 81689177 in words is "eighty-one million, six hundred eighty-nine thousand, one hundred seventy-seven".