81943320 has 64 divisors (see below), whose sum is σ = 248300640. Its totient is φ = 21632000.

The previous prime is 81943307. The next prime is 81943331. The reversal of 81943320 is 2334918.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8740 + ... + 15500.

Almost surely, 2^81943320 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81943320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124150320).

81943320 is an abundant number, since it is smaller than the sum of its proper divisors (166357320).

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

81943320 is a wasteful number, since it uses less digits than its factorization.

81943320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6876 (or 6872 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 30.

The square root of 81943320 is about 9052.2549676862. The cubic root of 81943320 is about 434.3480258253.

The spelling of 81943320 in words is "eighty-one million, nine hundred forty-three thousand, three hundred twenty".