816465521 has 4 divisors (see below), whose sum is σ = 816617700. Its totient is φ = 816313344.

The previous prime is 816465509. The next prime is 816465539. The reversal of 816465521 is 125564618.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 486643600 + 329821921 = 22060^2 + 18161^2 .

It is a cyclic number.

It is not a de Polignac number, because 816465521 - 2⁶ = 816465457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (816465571) 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, 67736 + ... + 78873.

It is an arithmetic number, because the mean of its divisors is an integer number (204154425).

Almost surely, 2^816465521 is an apocalyptic number.

It is an amenable number.

816465521 is a deficient number, since it is larger than the sum of its proper divisors (152179).

816465521 is a wasteful number, since it uses less digits than its factorization.

816465521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152178.

The product of its digits is 57600, while the sum is 38.

The square root of 816465521 is about 28573.8607996889. The cubic root of 816465521 is about 934.6434134532.

The spelling of 816465521 in words is "eight hundred sixteen million, four hundred sixty-five thousand, five hundred twenty-one".