81805965 has 8 divisors (see below), whose sum is σ = 130889568. Its totient is φ = 43629840.

The previous prime is 81805943. The next prime is 81805967. The reversal of 81805965 is 56950818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81805965 - 2⁶ = 81805901 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81805967) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2726851 + ... + 2726880.

It is an arithmetic number, because the mean of its divisors is an integer number (16361196).

Almost surely, 2^81805965 is an apocalyptic number.

It is an amenable number.

81805965 is a deficient number, since it is larger than the sum of its proper divisors (49083603).

81805965 is a wasteful number, since it uses less digits than its factorization.

81805965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5453739.

The product of its (nonzero) digits is 86400, while the sum is 42.

The square root of 81805965 is about 9044.6650020882. The cubic root of 81805965 is about 434.1052025400.

The spelling of 81805965 in words is "eighty-one million, eight hundred five thousand, nine hundred sixty-five".