816494221 has 4 divisors (see below), whose sum is σ = 821503552. Its totient is φ = 811484892.

The previous prime is 816494219. The next prime is 816494291. The reversal of 816494221 is 122494618.

816494221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 816494221 - 2¹ = 816494219 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 (816494291) 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, 2504421 + ... + 2504746.

It is an arithmetic number, because the mean of its divisors is an integer number (205375888).

Almost surely, 2^816494221 is an apocalyptic number.

It is an amenable number.

816494221 is a deficient number, since it is larger than the sum of its proper divisors (5009331).

816494221 is a wasteful number, since it uses less digits than its factorization.

816494221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5009330.

The product of its digits is 27648, while the sum is 37.

The square root of 816494221 is about 28574.3630025238. The cubic root of 816494221 is about 934.6543647022.

The spelling of 816494221 in words is "eight hundred sixteen million, four hundred ninety-four thousand, two hundred twenty-one".