817291221 has 4 divisors (see below), whose sum is σ = 1089721632. Its totient is φ = 544860812.

The previous prime is 817291207. The next prime is 817291229. The reversal of 817291221 is 122192718.

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 not a de Polignac number, because 817291221 - 2¹⁰ = 817290197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (817291229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 136215201 + ... + 136215206.

It is an arithmetic number, because the mean of its divisors is an integer number (272430408).

Almost surely, 2^817291221 is an apocalyptic number.

It is an amenable number.

817291221 is a deficient number, since it is larger than the sum of its proper divisors (272430411).

817291221 is a wasteful number, since it uses less digits than its factorization.

817291221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272430410.

The product of its digits is 4032, while the sum is 33.

The square root of 817291221 is about 28588.3056685771. The cubic root of 817291221 is about 934.9583788082.

The spelling of 817291221 in words is "eight hundred seventeen million, two hundred ninety-one thousand, two hundred twenty-one".