81204312 has 64 divisors (see below), whose sum is σ = 234662400. Its totient is φ = 22936320.

The previous prime is 81204311. The next prime is 81204341. The reversal of 81204312 is 21340218.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81204311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12237 + ... + 17667.

It is an arithmetic number, because the mean of its divisors is an integer number (3666600).

Almost surely, 2^81204312 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 81204312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117331200).

81204312 is an abundant number, since it is smaller than the sum of its proper divisors (153458088).

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

81204312 is a wasteful number, since it uses less digits than its factorization.

81204312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5536 (or 5532 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 81204312 is about 9011.3435180333. The cubic root of 81204312 is about 433.0383544084.

The spelling of 81204312 in words is "eighty-one million, two hundred four thousand, three hundred twelve".