81682221 has 4 divisors (see below), whose sum is σ = 108909632. Its totient is φ = 54454812.

The previous prime is 81682217. The next prime is 81682231. The reversal of 81682221 is 12228618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81682221 - 2² = 81682217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81682201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13613701 + ... + 13613706.

It is an arithmetic number, because the mean of its divisors is an integer number (27227408).

Almost surely, 2^81682221 is an apocalyptic number.

It is an amenable number.

81682221 is a deficient number, since it is larger than the sum of its proper divisors (27227411).

81682221 is a wasteful number, since it uses less digits than its factorization.

81682221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27227410.

The product of its digits is 3072, while the sum is 30.

The square root of 81682221 is about 9037.8216955193. The cubic root of 81682221 is about 433.8862086378.

The spelling of 81682221 in words is "eighty-one million, six hundred eighty-two thousand, two hundred twenty-one".