21023421 has 8 divisors (see below), whose sum is σ = 28063680. Its totient is φ = 13999392.

The previous prime is 21023419. The next prime is 21023459. The reversal of 21023421 is 12432012.

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

It is not a de Polignac number, because 21023421 - 2¹ = 21023419 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21023421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21027421) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 616 + ... + 6513.

It is an arithmetic number, because the mean of its divisors is an integer number (3507960).

Almost surely, 2^21023421 is an apocalyptic number.

It is an amenable number.

21023421 is a deficient number, since it is larger than the sum of its proper divisors (7040259).

21023421 is an equidigital number, since it uses as much as digits as its factorization.

21023421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8115.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21023421 is about 4585.1304234449. The cubic root of 21023421 is about 275.9949458222.

Adding to 21023421 its reverse (12432012), we get a palindrome (33455433).

The spelling of 21023421 in words is "twenty-one million, twenty-three thousand, four hundred twenty-one".