1990421 has 4 divisors (see below), whose sum is σ = 2095200. Its totient is φ = 1885644.

The previous prime is 1990381. The next prime is 1990433. The reversal of 1990421 is 1240991.

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 a de Polignac number, because none of the positive numbers 2^k-1990421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1990441) 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, 52361 + ... + 52398.

It is an arithmetic number, because the mean of its divisors is an integer number (523800).

2^1990421 is an apocalyptic number.

It is an amenable number.

1990421 is a deficient number, since it is larger than the sum of its proper divisors (104779).

1990421 is a wasteful number, since it uses less digits than its factorization.

1990421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104778.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 1990421 is about 1410.8228095689. The cubic root of 1990421 is about 125.7906366064.

The spelling of 1990421 in words is "one million, nine hundred ninety thousand, four hundred twenty-one".