816621 has 8 divisors (see below), whose sum is σ = 1172640. Its totient is φ = 502512.

The previous prime is 816593. The next prime is 816649. The reversal of 816621 is 126618.

It is an interprime number because it is at equal distance from previous prime (816593) and next prime (816649).

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

It is not a de Polignac number, because 816621 - 2⁵ = 816589 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 816591 and 816600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816691) 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 7 ways as a sum of consecutive naturals, for example, 10431 + ... + 10508.

It is an arithmetic number, because the mean of its divisors is an integer number (146580).

2⁸¹⁶⁶²¹ is an apocalyptic number.

It is an amenable number.

816621 is a deficient number, since it is larger than the sum of its proper divisors (356019).

816621 is a wasteful number, since it uses less digits than its factorization.

816621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20955.

The product of its digits is 576, while the sum is 24.

The square root of 816621 is about 903.6708471562. The cubic root of 816621 is about 93.4702737534.

The spelling of 816621 in words is "eight hundred sixteen thousand, six hundred twenty-one".