816506621 has 8 divisors (see below), whose sum is σ = 941872320. Its totient is φ = 693321408.

The previous prime is 816506611. The next prime is 816506623. The reversal of 816506621 is 126605618.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 816506621 - 2¹⁴ = 816490237 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816506623) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 544316 + ... + 545813.

It is an arithmetic number, because the mean of its divisors is an integer number (117734040).

Almost surely, 2^816506621 is an apocalyptic number.

It is an amenable number.

816506621 is a deficient number, since it is larger than the sum of its proper divisors (125365699).

816506621 is a wasteful number, since it uses less digits than its factorization.

816506621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1090243.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 816506621 is about 28574.5799794153. The cubic root of 816506621 is about 934.6590961729.

The spelling of 816506621 in words is "eight hundred sixteen million, five hundred six thousand, six hundred twenty-one".