81965646 has 48 divisors (see below), whose sum is σ = 203490144. Its totient is φ = 23357952.

The previous prime is 81965633. The next prime is 81965647. The reversal of 81965646 is 64656918.

81965646 is a `hidden beast` number, since 81 + 9 + 6 + 564 + 6 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81965647) 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 23 ways as a sum of consecutive naturals, for example, 74170 + ... + 75266.

It is an arithmetic number, because the mean of its divisors is an integer number (4239378).

Almost surely, 2^81965646 is an apocalyptic number.

81965646 is an abundant number, since it is smaller than the sum of its proper divisors (121524498).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81965646 is a wasteful number, since it uses less digits than its factorization.

81965646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1705 (or 1702 counting only the distinct ones).

The product of its digits is 311040, while the sum is 45.

The square root of 81965646 is about 9053.4880570971. The cubic root of 81965646 is about 434.3874692416.

The spelling of 81965646 in words is "eighty-one million, nine hundred sixty-five thousand, six hundred forty-six".