81964530 has 96 divisors (see below), whose sum is σ = 219967488. Its totient is φ = 21168000.

The previous prime is 81964529. The next prime is 81964543. The reversal of 81964530 is 3546918.

81964530 is a `hidden beast` number, since 8 + 1 + 9 + 645 + 3 + 0 = 666.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 645327 + ... + 645453.

It is an arithmetic number, because the mean of its divisors is an integer number (2291328).

Almost surely, 2^81964530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81964530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109983744).

81964530 is an abundant number, since it is smaller than the sum of its proper divisors (138002958).

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

81964530 is a wasteful number, since it uses less digits than its factorization.

81964530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312 (or 309 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 81964530 is about 9053.4264231837. The cubic root of 81964530 is about 434.3854977709.

The spelling of 81964530 in words is "eighty-one million, nine hundred sixty-four thousand, five hundred thirty".