63821 has 4 divisors (see below), whose sum is σ = 67200. Its totient is φ = 60444.

The previous prime is 63809. The next prime is 63823. The reversal of 63821 is 12836.

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 a de Polignac number, because none of the positive numbers 2^k-63821 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 = 63793 and 63802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1661 + ... + 1698.

It is an arithmetic number, because the mean of its divisors is an integer number (16800).

2⁶³⁸²¹ is an apocalyptic number.

It is an amenable number.

63821 is a deficient number, since it is larger than the sum of its proper divisors (3379).

63821 is a wasteful number, since it uses less digits than its factorization.

63821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3378.

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

The square root of 63821 is about 252.6281852842. The cubic root of 63821 is about 39.9626735125.

The spelling of 63821 in words is "sixty-three thousand, eight hundred twenty-one".