81315828 has 144 divisors (see below), whose sum is σ = 243419904. Its totient is φ = 22609920.

The previous prime is 81315809. The next prime is 81315841. The reversal of 81315828 is 82851318.

It is a super-2 number, since 2×81315828² = 13224527766651168, which contains 22 as substring.

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 = 81315792 and 81315801.

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, 316276 + ... + 316532.

It is an arithmetic number, because the mean of its divisors is an integer number (1690416).

Almost surely, 2^81315828 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 81315828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121709952).

81315828 is an abundant number, since it is smaller than the sum of its proper divisors (162104076).

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

81315828 is a wasteful number, since it uses less digits than its factorization.

81315828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342 (or 337 counting only the distinct ones).

The product of its digits is 15360, while the sum is 36.

The square root of 81315828 is about 9017.5289298122. The cubic root of 81315828 is about 433.2364909166.

It can be divided in two parts, 813 and 15828, that added together give a square (16641 = 129²).

The spelling of 81315828 in words is "eighty-one million, three hundred fifteen thousand, eight hundred twenty-eight".