1920821 has 4 divisors (see below), whose sum is σ = 2195232. Its totient is φ = 1646412.

The previous prime is 1920817. The next prime is 1920839. The reversal of 1920821 is 1280291.

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 1920821 - 2² = 1920817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1920811) 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, 137195 + ... + 137208.

It is an arithmetic number, because the mean of its divisors is an integer number (548808).

2^1920821 is an apocalyptic number.

It is an amenable number.

1920821 is a deficient number, since it is larger than the sum of its proper divisors (274411).

1920821 is an equidigital number, since it uses as much as digits as its factorization.

1920821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274410.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 1920821 is about 1385.9368672490. The cubic root of 1920821 is about 124.3070132546.

The spelling of 1920821 in words is "one million, nine hundred twenty thousand, eight hundred twenty-one".