990421 has 4 divisors (see below), whose sum is σ = 992844. Its totient is φ = 988000.

The previous prime is 990397. The next prime is 990463. The reversal of 990421 is 124099.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 124099 = 193 ⋅643.

It can be written as a sum of positive squares in 2 ways, for example, as 171396 + 819025 = 414^2 + 905^2 .

It is a cyclic number.

It is not a de Polignac number, because 990421 - 2⁵ = 990389 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 (910421) 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, 430 + ... + 1471.

It is an arithmetic number, because the mean of its divisors is an integer number (248211).

2⁹⁹⁰⁴²¹ is an apocalyptic number.

It is an amenable number.

990421 is a deficient number, since it is larger than the sum of its proper divisors (2423).

990421 is a wasteful number, since it uses less digits than its factorization.

990421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2422.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 990421 is about 995.1989750799. The cubic root of 990421 is about 99.6796750146.

The spelling of 990421 in words is "nine hundred ninety thousand, four hundred twenty-one".