81312200 has 24 divisors (see below), whose sum is σ = 189051330. Its totient is φ = 32524800.

The previous prime is 81312197. The next prime is 81312211. The reversal of 81312200 is 221318.

It can be written as a sum of positive squares in 3 ways, for example, as 42797764 + 38514436 = 6542^2 + 6206^2 .

It is a super-2 number, since 2×81312200² = 13223347737680000, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 203081 + ... + 203480.

Almost surely, 2^81312200 is an apocalyptic number.

It is an amenable number.

81312200 is an abundant number, since it is smaller than the sum of its proper divisors (107739130).

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

81312200 is a wasteful number, since it uses less digits than its factorization.

81312200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 406577 (or 406568 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 81312200 is about 9017.3277638112. The cubic root of 81312200 is about 433.2300477045.

Adding to 81312200 its reverse (221318), we get a palindrome (81533518).

It can be divided in two parts, 8 and 1312200, that multiplied together give a square (10497600 = 3240²).

The spelling of 81312200 in words is "eighty-one million, three hundred twelve thousand, two hundred".