81312510 has 64 divisors (see below), whose sum is σ = 200247552. Its totient is φ = 21125376.

The previous prime is 81312503. The next prime is 81312551. The reversal of 81312510 is 1521318.

It is a super-2 number, since 2×81312510² = 13223448565000200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 234157 + ... + 234503.

It is an arithmetic number, because the mean of its divisors is an integer number (3128868).

Almost surely, 2^81312510 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81312510, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100123776).

81312510 is an abundant number, since it is smaller than the sum of its proper divisors (118935042).

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

81312510 is a wasteful number, since it uses less digits than its factorization.

81312510 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 537.

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 81312510 is about 9017.3449529227. The cubic root of 81312510 is about 433.2305982621.

Adding to 81312510 its reverse (1521318), we get a palindrome (82833828).

The spelling of 81312510 in words is "eighty-one million, three hundred twelve thousand, five hundred ten".