817672721 has 4 divisors (see below), whose sum is σ = 818667072. Its totient is φ = 816678372.

The previous prime is 817672693. The next prime is 817672727. The reversal of 817672721 is 127276718.

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 817672721 - 2¹⁴ = 817656337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (817672727) 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 3 ways as a sum of consecutive naturals, for example, 495941 + ... + 497586.

It is an arithmetic number, because the mean of its divisors is an integer number (204666768).

Almost surely, 2^817672721 is an apocalyptic number.

It is an amenable number.

817672721 is a deficient number, since it is larger than the sum of its proper divisors (994351).

817672721 is an equidigital number, since it uses as much as digits as its factorization.

817672721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 994350.

The product of its digits is 65856, while the sum is 41.

The square root of 817672721 is about 28594.9771988019. The cubic root of 817672721 is about 935.1038313014.

The spelling of 817672721 in words is "eight hundred seventeen million, six hundred seventy-two thousand, seven hundred twenty-one".