1890021 has 8 divisors (see below), whose sum is σ = 2880064. Its totient is φ = 1080000.

The previous prime is 1890019. The next prime is 1890023. The reversal of 1890021 is 1200981.

It is an interprime number because it is at equal distance from previous prime (1890019) and next prime (1890023).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1890021 - 2¹ = 1890019 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 90001 = 1890021 / (1 + 8 + 9 + 0 + 0 + 2 + 1).

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1890021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1890023) 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 7 ways as a sum of consecutive naturals, for example, 44980 + ... + 45021.

It is an arithmetic number, because the mean of its divisors is an integer number (360008).

2^1890021 is an apocalyptic number.

It is an amenable number.

1890021 is a deficient number, since it is larger than the sum of its proper divisors (990043).

1890021 is an equidigital number, since it uses as much as digits as its factorization.

1890021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90011.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 1890021 is about 1374.7803460917. The cubic root of 1890021 is about 123.6390169131.

It can be divided in two parts, 18900 and 21, that multiplied together give a square (396900 = 630²).

The spelling of 1890021 in words is "one million, eight hundred ninety thousand, twenty-one".