1243821 has 4 divisors (see below), whose sum is σ = 1658432. Its totient is φ = 829212.

The previous prime is 1243819. The next prime is 1243841. The reversal of 1243821 is 1283421.

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 not a de Polignac number, because 1243821 - 2¹ = 1243819 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1243811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 207301 + ... + 207306.

It is an arithmetic number, because the mean of its divisors is an integer number (414608).

2^1243821 is an apocalyptic number.

It is an amenable number.

1243821 is a deficient number, since it is larger than the sum of its proper divisors (414611).

1243821 is an equidigital number, since it uses as much as digits as its factorization.

1243821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414610.

The product of its digits is 384, while the sum is 21.

The square root of 1243821 is about 1115.2672325501. The cubic root of 1243821 is about 107.5439445359.

The spelling of 1243821 in words is "one million, two hundred forty-three thousand, eight hundred twenty-one".