81247320 has 256 divisors, whose sum is σ = 337996800. Its totient is φ = 16865280.

The previous prime is 81247291. The next prime is 81247381. The reversal of 81247320 is 2374218.

It is a super-2 number, since 2×81247320² = 13202254014364800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 82672 + ... + 83648.

It is an arithmetic number, because the mean of its divisors is an integer number (1320300).

Almost surely, 2^81247320 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 81247320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (168998400).

81247320 is an abundant number, since it is smaller than the sum of its proper divisors (256749480).

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

81247320 is a wasteful number, since it uses less digits than its factorization.

81247320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1015 (or 1005 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 81247320 is about 9013.7295277815. The cubic root of 81247320 is about 433.1147905241.

The spelling of 81247320 in words is "eighty-one million, two hundred forty-seven thousand, three hundred twenty".