402821 has 4 divisors (see below), whose sum is σ = 408000. Its totient is φ = 397644.

The previous prime is 402817. The next prime is 402823. The reversal of 402821 is 128204.

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 402821 - 2² = 402817 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 402821.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 402821.

It is not an unprimeable number, because it can be changed into a prime (402823) 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, 2471 + ... + 2628.

It is an arithmetic number, because the mean of its divisors is an integer number (102000).

2⁴⁰²⁸²¹ is an apocalyptic number.

It is an amenable number.

402821 is a deficient number, since it is larger than the sum of its proper divisors (5179).

402821 is an equidigital number, since it uses as much as digits as its factorization.

402821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5178.

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 402821 is about 634.6818100434. The cubic root of 402821 is about 73.8534352518.

The spelling of 402821 in words is "four hundred two thousand, eight hundred twenty-one".