81935969 has 4 divisors (see below), whose sum is σ = 82255044. Its totient is φ = 81616896.

The previous prime is 81935963. The next prime is 81935977. The reversal of 81935969 is 96953918.

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 79423744 + 2512225 = 8912^2 + 1585^2 .

It is a cyclic number.

It is not a de Polignac number, because 81935969 - 2²⁰ = 80887393 is a prime.

It is a super-2 number, since 2×81935969² = 13427006031937922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81935963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 159152 + ... + 159665.

It is an arithmetic number, because the mean of its divisors is an integer number (20563761).

Almost surely, 2^81935969 is an apocalyptic number.

It is an amenable number.

81935969 is a deficient number, since it is larger than the sum of its proper divisors (319075).

81935969 is a wasteful number, since it uses less digits than its factorization.

81935969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319074.

The product of its digits is 524880, while the sum is 50.

The square root of 81935969 is about 9051.8489271529. The cubic root of 81935969 is about 434.3350372220.

The spelling of 81935969 in words is "eighty-one million, nine hundred thirty-five thousand, nine hundred sixty-nine".