81689797 has 16 divisors (see below), whose sum is σ = 99894400. Its totient is φ = 65240640.

The previous prime is 81689789. The next prime is 81689819. The reversal of 81689797 is 79798618.

It is a cyclic number.

It is not a de Polignac number, because 81689797 - 2³ = 81689789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81689717) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3079 + ... + 13147.

It is an arithmetic number, because the mean of its divisors is an integer number (6243400).

Almost surely, 2^81689797 is an apocalyptic number.

It is an amenable number.

81689797 is a deficient number, since it is larger than the sum of its proper divisors (18204603).

81689797 is a wasteful number, since it uses less digits than its factorization.

81689797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10156.

The product of its digits is 1524096, while the sum is 55.

The square root of 81689797 is about 9038.2408133442. The cubic root of 81689797 is about 433.8996224924.

The spelling of 81689797 in words is "eighty-one million, six hundred eighty-nine thousand, seven hundred ninety-seven".