81974340 has 288 divisors, whose sum is σ = 311351040. Its totient is φ = 17031168.

The previous prime is 81974317. The next prime is 81974353. The reversal of 81974340 is 4347918.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81974295 and 81974304.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 921016 + ... + 921104.

It is an arithmetic number, because the mean of its divisors is an integer number (1081080).

Almost surely, 2^81974340 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 81974340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (155675520).

81974340 is an abundant number, since it is smaller than the sum of its proper divisors (229376700).

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

81974340 is a wasteful number, since it uses less digits than its factorization.

81974340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171 (or 166 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 81974340 is about 9053.9681907990. The cubic root of 81974340 is about 434.4028270219.

The spelling of 81974340 in words is "eighty-one million, nine hundred seventy-four thousand, three hundred forty".