81276829920 has 768 divisors, whose sum is σ = 336825216000. Its totient is φ = 18045296640.

The previous prime is 81276829897. The next prime is 81276829927. The reversal of 81276829920 is 2992867218.

81276829920 is a `hidden beast` number, since 81 + 276 + 8 + 299 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81276829927) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 92045799 + ... + 92046681.

It is an arithmetic number, because the mean of its divisors is an integer number (438574500).

Almost surely, 2^81276829920 is an apocalyptic number.

81276829920 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 81276829920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (168412608000).

81276829920 is an abundant number, since it is smaller than the sum of its proper divisors (255548386080).

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

81276829920 is a wasteful number, since it uses less digits than its factorization.

81276829920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1080 (or 1066 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 54.

The spelling of 81276829920 in words is "eighty-one billion, two hundred seventy-six million, eight hundred twenty-nine thousand, nine hundred twenty".