816721441 has 4 divisors (see below), whose sum is σ = 859706800. Its totient is φ = 773736084.

The previous prime is 816721439. The next prime is 816721453. The reversal of 816721441 is 144127618.

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 not a de Polignac number, because 816721441 - 2¹ = 816721439 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 816721397 and 816721406.

It is not an unprimeable number, because it can be changed into a prime (816721471) 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, 21492651 + ... + 21492688.

It is an arithmetic number, because the mean of its divisors is an integer number (214926700).

Almost surely, 2^816721441 is an apocalyptic number.

It is an amenable number.

816721441 is a deficient number, since it is larger than the sum of its proper divisors (42985359).

816721441 is a wasteful number, since it uses less digits than its factorization.

816721441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42985358.

The product of its digits is 10752, while the sum is 34.

The square root of 816721441 is about 28578.3386675993. The cubic root of 816721441 is about 934.7410574847.

The spelling of 816721441 in words is "eight hundred sixteen million, seven hundred twenty-one thousand, four hundred forty-one".