81217229 has 4 divisors (see below), whose sum is σ = 85491840. Its totient is φ = 76942620.

The previous prime is 81217151. The next prime is 81217237. The reversal of 81217229 is 92271218.

It is a happy number.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81217229 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81217195 and 81217204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81217289) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2137277 + ... + 2137314.

It is an arithmetic number, because the mean of its divisors is an integer number (21372960).

Almost surely, 2^81217229 is an apocalyptic number.

It is an amenable number.

81217229 is a deficient number, since it is larger than the sum of its proper divisors (4274611).

81217229 is a wasteful number, since it uses less digits than its factorization.

81217229 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4274610.

The product of its digits is 4032, while the sum is 32.

The square root of 81217229 is about 9012.0601973134. The cubic root of 81217229 is about 433.0613140261.

The spelling of 81217229 in words is "eighty-one million, two hundred seventeen thousand, two hundred twenty-nine".