81355530 has 64 divisors (see below), whose sum is σ = 209485440. Its totient is φ = 20157696.

The previous prime is 81355493. The next prime is 81355541. The reversal of 81355530 is 3555318.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28864 + ... + 31556.

It is an arithmetic number, because the mean of its divisors is an integer number (3273210).

Almost surely, 2^81355530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81355530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104742720).

81355530 is an abundant number, since it is smaller than the sum of its proper divisors (128129910).

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

81355530 is a wasteful number, since it uses less digits than its factorization.

81355530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2775.

The product of its (nonzero) digits is 9000, while the sum is 30.

The square root of 81355530 is about 9019.7300403061. The cubic root of 81355530 is about 433.3069878789.

The spelling of 81355530 in words is "eighty-one million, three hundred fifty-five thousand, five hundred thirty".