630821 has 4 divisors (see below), whose sum is σ = 658272. Its totient is φ = 603372.

The previous prime is 630803. The next prime is 630823. The reversal of 630821 is 128036.

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 630821 - 2¹⁴ = 614437 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 630793 and 630802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (630823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13691 + ... + 13736.

It is an arithmetic number, because the mean of its divisors is an integer number (164568).

2⁶³⁰⁸²¹ is an apocalyptic number.

It is an amenable number.

630821 is a deficient number, since it is larger than the sum of its proper divisors (27451).

630821 is a wasteful number, since it uses less digits than its factorization.

630821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27450.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 630821 is about 794.2424063219. The cubic root of 630821 is about 85.7634113893.

Adding to 630821 its reverse (128036), we get a palindrome (758857).

The spelling of 630821 in words is "six hundred thirty thousand, eight hundred twenty-one".