1021821 has 16 divisors (see below), whose sum is σ = 1451520. Its totient is φ = 638000.

The previous prime is 1021807. The next prime is 1021831. The reversal of 1021821 is 1281201.

It is a cyclic number.

It is not a de Polignac number, because 1021821 - 2¹⁰ = 1020797 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1021821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021831) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3946 + ... + 4196.

It is an arithmetic number, because the mean of its divisors is an integer number (90720).

2^1021821 is an apocalyptic number.

It is an amenable number.

1021821 is a deficient number, since it is larger than the sum of its proper divisors (429699).

1021821 is a wasteful number, since it uses less digits than its factorization.

1021821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336.

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 1021821 is about 1010.8516211591. The cubic root of 1021821 is about 100.7221392627.

The spelling of 1021821 in words is "one million, twenty-one thousand, eight hundred twenty-one".