81229680 has 240 divisors, whose sum is σ = 317551104. Its totient is φ = 18224640.

The previous prime is 81229679. The next prime is 81229691. The reversal of 81229680 is 8692218.

It is a tau number, because it is divible by the number of its divisors (240).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent 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, 357727 + ... + 357953.

Almost surely, 2^81229680 is an apocalyptic number.

81229680 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 81229680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158775552).

81229680 is an abundant number, since it is smaller than the sum of its proper divisors (236321424).

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

81229680 is a wasteful number, since it uses less digits than its factorization.

81229680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324 (or 315 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 81229680 is about 9012.7509673795. The cubic root of 81229680 is about 433.0834430372.

The spelling of 81229680 in words is "eighty-one million, two hundred twenty-nine thousand, six hundred eighty".