81885697 has 4 divisors (see below), whose sum is σ = 81912276. Its totient is φ = 81859120.

The previous prime is 81885691. The next prime is 81885707. The reversal of 81885697 is 79658818.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10246401 + 71639296 = 3201^2 + 8464^2 .

It is a cyclic number.

It is not a de Polignac number, because 81885697 - 2²³ = 73497089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81885691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7954 + ... + 15067.

It is an arithmetic number, because the mean of its divisors is an integer number (20478069).

Almost surely, 2^81885697 is an apocalyptic number.

It is an amenable number.

81885697 is a deficient number, since it is larger than the sum of its proper divisors (26579).

81885697 is a wasteful number, since it uses less digits than its factorization.

81885697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26578.

The product of its digits is 967680, while the sum is 52.

The square root of 81885697 is about 9049.0716098393. The cubic root of 81885697 is about 434.2461899657.

The spelling of 81885697 in words is "eighty-one million, eight hundred eighty-five thousand, six hundred ninety-seven".