421021 has 4 divisors (see below), whose sum is σ = 443200. Its totient is φ = 398844.

The previous prime is 421019. The next prime is 421033. The reversal of 421021 is 120124.

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 421021 - 2¹ = 421019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 420989 and 421007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11061 + ... + 11098.

It is an arithmetic number, because the mean of its divisors is an integer number (110800).

2⁴²¹⁰²¹ is an apocalyptic number.

It is an amenable number.

421021 is a deficient number, since it is larger than the sum of its proper divisors (22179).

421021 is a wasteful number, since it uses less digits than its factorization.

421021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22178.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 421021 is about 648.8613102967. The cubic root of 421021 is about 74.9493584060.

Adding to 421021 its reverse (120124), we get a palindrome (541145).

It can be divided in two parts, 4210 and 21, that multiplied together give a triangular number (88410 = T₄₂₀).

The spelling of 421021 in words is "four hundred twenty-one thousand, twenty-one", and thus it is an iban number.