616821 has 4 divisors (see below), whose sum is σ = 822432. Its totient is φ = 411212.

The previous prime is 616799. The next prime is 616829. The reversal of 616821 is 128616.

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 616821 - 2⁵ = 616789 is a prime.

It is a D-number.

616821 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 616791 and 616800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (616829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102801 + ... + 102806.

It is an arithmetic number, because the mean of its divisors is an integer number (205608).

2⁶¹⁶⁸²¹ is an apocalyptic number.

It is an amenable number.

616821 is a deficient number, since it is larger than the sum of its proper divisors (205611).

616821 is a wasteful number, since it uses less digits than its factorization.

616821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205610.

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

The square root of 616821 is about 785.3795260891. The cubic root of 616821 is about 85.1242013592.

The spelling of 616821 in words is "six hundred sixteen thousand, eight hundred twenty-one".