817942221 has 12 divisors (see below), whose sum is σ = 1196428480. Its totient is φ = 538391880.

The previous prime is 817942219. The next prime is 817942247. The reversal of 817942221 is 122249718.

It is not a de Polignac number, because 817942221 - 2¹ = 817942219 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 (817942201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 574495 + ... + 575916.

Almost surely, 2^817942221 is an apocalyptic number.

It is an amenable number.

817942221 is a deficient number, since it is larger than the sum of its proper divisors (378486259).

817942221 is a wasteful number, since it uses less digits than its factorization.

817942221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1150496 (or 1150493 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 817942221 is about 28599.6891766327. The cubic root of 817942221 is about 935.2065548785.

The spelling of 817942221 in words is "eight hundred seventeen million, nine hundred forty-two thousand, two hundred twenty-one".