81689711 has 2 divisors, whose sum is σ = 81689712. Its totient is φ = 81689710.

The previous prime is 81689677. The next prime is 81689717. The reversal of 81689711 is 11798618.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81689711 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81689717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40844855 + 40844856.

It is an arithmetic number, because the mean of its divisors is an integer number (40844856).

Almost surely, 2^81689711 is an apocalyptic number.

81689711 is a deficient number, since it is larger than the sum of its proper divisors (1).

81689711 is an equidigital number, since it uses as much as digits as its factorization.

81689711 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 41.

The square root of 81689711 is about 9038.2360557799. The cubic root of 81689711 is about 433.8994702278.

The spelling of 81689711 in words is "eighty-one million, six hundred eighty-nine thousand, seven hundred eleven".