81540900 has 243 divisors, whose sum is σ = 304388721. Its totient is φ = 18204480.

The previous prime is 81540889. The next prime is 81540929. The reversal of 81540900 is 904518.

The square root of 81540900 is 9030.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 29354724 + 52186176 = 5418^2 + 7224^2 .

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 80 ways as a sum of consecutive naturals, for example, 1896279 + ... + 1896321.

Almost surely, 2^81540900 is an apocalyptic number.

81540900 is the 9030-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81540900

81540900 is an abundant number, since it is smaller than the sum of its proper divisors (222847821).

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

81540900 is a wasteful number, since it uses less digits than its factorization.

81540900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120 (or 60 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The cubic root of 81540900 is about 433.6358374291.

The spelling of 81540900 in words is "eighty-one million, five hundred forty thousand, nine hundred".