81974880 has 288 divisors, whose sum is σ = 313709760. Its totient is φ = 19353600.

The previous prime is 81974861. The next prime is 81974887. The reversal of 81974880 is 8847918.

81974880 is a `hidden beast` number, since 81 + 97 + 488 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81974887) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 542805 + ... + 542955.

It is an arithmetic number, because the mean of its divisors is an integer number (1089270).

Almost surely, 2^81974880 is an apocalyptic number.

81974880 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81974880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (156854880).

81974880 is an abundant number, since it is smaller than the sum of its proper divisors (231734880).

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

81974880 is a wasteful number, since it uses less digits than its factorization.

81974880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214 (or 203 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 81974880 is about 9053.9980119282. The cubic root of 81974880 is about 434.4037808855.

The spelling of 81974880 in words is "eighty-one million, nine hundred seventy-four thousand, eight hundred eighty".