81897965 has 4 divisors (see below), whose sum is σ = 98277564. Its totient is φ = 65518368.

The previous prime is 81897953. The next prime is 81897979. The reversal of 81897965 is 56979818.

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 25542916 + 56355049 = 5054^2 + 7507^2 .

It is a cyclic number.

It is not a de Polignac number, because 81897965 - 2⁸ = 81897709 is a prime.

It is a super-2 number, since 2×81897965² = 13414553342282450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8189792 + ... + 8189801.

It is an arithmetic number, because the mean of its divisors is an integer number (24569391).

Almost surely, 2^81897965 is an apocalyptic number.

It is an amenable number.

81897965 is a deficient number, since it is larger than the sum of its proper divisors (16379599).

81897965 is a wasteful number, since it uses less digits than its factorization.

81897965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16379598.

The product of its digits is 1088640, while the sum is 53.

The square root of 81897965 is about 9049.7494440454. The cubic root of 81897965 is about 434.2678749340.

The spelling of 81897965 in words is "eighty-one million, eight hundred ninety-seven thousand, nine hundred sixty-five".