81216204 has 24 divisors (see below), whose sum is σ = 189681408. Its totient is φ = 27046800.

The previous prime is 81216199. The next prime is 81216209. The reversal of 81216204 is 40261218.

81216204 = 3000² + 3001² + ... + 3008².

It is an interprime number because it is at equal distance from previous prime (81216199) and next prime (81216209).

It is not an unprimeable number, because it can be changed into a prime (81216209) 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 7 ways as a sum of consecutive naturals, for example, 13929 + ... + 18879.

It is an arithmetic number, because the mean of its divisors is an integer number (7903392).

Almost surely, 2^81216204 is an apocalyptic number.

It is an amenable number.

81216204 is an abundant number, since it is smaller than the sum of its proper divisors (108465204).

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

81216204 is a wasteful number, since it uses less digits than its factorization.

81216204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6325 (or 6323 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 81216204 is about 9012.0033288942. The cubic root of 81216204 is about 433.0594922052.

The spelling of 81216204 in words is "eighty-one million, two hundred sixteen thousand, two hundred four".