81505300 has 18 divisors (see below), whose sum is σ = 176866718. Its totient is φ = 32602080.

The previous prime is 81505297. The next prime is 81505301. The reversal of 81505300 is 350518.

It can be written as a sum of positive squares in 3 ways, for example, as 21566736 + 59938564 = 4644^2 + 7742^2 .

It is a super-2 number, since 2×81505300² = 13286227856180000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81505301) by changing a digit.

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, 407427 + ... + 407626.

Almost surely, 2^81505300 is an apocalyptic number.

It is an amenable number.

81505300 is an abundant number, since it is smaller than the sum of its proper divisors (95361418).

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

81505300 is a wasteful number, since it uses less digits than its factorization.

81505300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 815067 (or 815060 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 81505300 is about 9028.0285777129. The cubic root of 81505300 is about 433.5727211158.

Adding to 81505300 its reverse (350518), we get a palindrome (81855818).

The spelling of 81505300 in words is "eighty-one million, five hundred five thousand, three hundred".