81510208 has 42 divisors (see below), whose sum is σ = 174747174. Its totient is φ = 37499904.

The previous prime is 81510203. The next prime is 81510227. The reversal of 81510208 is 80201518.

It can be written as a sum of positive squares in 3 ways, for example, as 19289664 + 62220544 = 4392^2 + 7888^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81510203) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 260260 + ... + 260572.

It is an arithmetic number, because the mean of its divisors is an integer number (4160647).

Almost surely, 2^81510208 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 81510208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87373587).

81510208 is an abundant number, since it is smaller than the sum of its proper divisors (93236966).

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

81510208 is an equidigital number, since it uses as much as digits as its factorization.

81510208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 651 (or 328 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 81510208 is about 9028.3003937618. The cubic root of 81510208 is about 433.5814237490.

It can be divided in two parts, 81510 and 208, that added together give a palindrome (81718).

The spelling of 81510208 in words is "eighty-one million, five hundred ten thousand, two hundred eight".