1920021 has 4 divisors (see below), whose sum is σ = 2560032. Its totient is φ = 1280012.

The previous prime is 1920013. The next prime is 1920043. The reversal of 1920021 is 1200291.

It is a happy number.

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 1920021 - 2³ = 1920013 is a prime.

It is a D-number.

It is a Curzon number.

1920021 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1920001) 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, 320001 + ... + 320006.

It is an arithmetic number, because the mean of its divisors is an integer number (640008).

2^1920021 is an apocalyptic number.

It is an amenable number.

1920021 is a deficient number, since it is larger than the sum of its proper divisors (640011).

1920021 is an equidigital number, since it uses as much as digits as its factorization.

1920021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 640010.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 1920021 is about 1385.6482237567. The cubic root of 1920021 is about 124.2897533746.

The spelling of 1920021 in words is "one million, nine hundred twenty thousand, twenty-one".