81550500 has 48 divisors (see below), whose sum is σ = 237479424. Its totient is φ = 21746400.

The previous prime is 81550493. The next prime is 81550507. The reversal of 81550500 is 505518.

It is an interprime number because it is at equal distance from previous prime (81550493) and next prime (81550507).

It is not an unprimeable number, because it can be changed into a prime (81550507) 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 15 ways as a sum of consecutive naturals, for example, 25684 + ... + 28683.

It is an arithmetic number, because the mean of its divisors is an integer number (4947488).

Almost surely, 2^81550500 is an apocalyptic number.

It is an amenable number.

81550500 is an abundant number, since it is smaller than the sum of its proper divisors (155928924).

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

81550500 is a wasteful number, since it uses less digits than its factorization.

81550500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54389 (or 54377 counting only the distinct ones).

The product of its (nonzero) digits is 1000, while the sum is 24.

The square root of 81550500 is about 9030.5315458172. The cubic root of 81550500 is about 433.6528544135.

It can be divided in two parts, 815 and 50500, that added together give a palindrome (51315).

The spelling of 81550500 in words is "eighty-one million, five hundred fifty thousand, five hundred".