1321821 has 12 divisors (see below), whose sum is σ = 1920672. Its totient is φ = 875976.

The previous prime is 1321813. The next prime is 1321823. The reversal of 1321821 is 1281231.

It is not a de Polignac number, because 1321821 - 2³ = 1321813 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1321794 and 1321803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321823) 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 11 ways as a sum of consecutive naturals, for example, 1720 + ... + 2366.

It is an arithmetic number, because the mean of its divisors is an integer number (160056).

2^1321821 is an apocalyptic number.

It is an amenable number.

1321821 is a deficient number, since it is larger than the sum of its proper divisors (598851).

1321821 is a wasteful number, since it uses less digits than its factorization.

1321821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 880 (or 877 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 1321821 is about 1149.7047447062. The cubic root of 1321821 is about 109.7465514697.

It can be divided in two parts, 132 and 1821, that added together give a triangular number (1953 = T₆₂).

The spelling of 1321821 in words is "one million, three hundred twenty-one thousand, eight hundred twenty-one".