20321421 has 4 divisors (see below), whose sum is σ = 27095232. Its totient is φ = 13547612.

The previous prime is 20321417. The next prime is 20321423. The reversal of 20321421 is 12412302.

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 20321421 - 2² = 20321417 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20321421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20321423) 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, 3386901 + ... + 3386906.

It is an arithmetic number, because the mean of its divisors is an integer number (6773808).

Almost surely, 2^20321421 is an apocalyptic number.

It is an amenable number.

20321421 is a deficient number, since it is larger than the sum of its proper divisors (6773811).

20321421 is an equidigital number, since it uses as much as digits as its factorization.

20321421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6773810.

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

The square root of 20321421 is about 4507.9286817784. The cubic root of 20321421 is about 272.8881587792. Note that the first 3 decimals are identical.

Adding to 20321421 its reverse (12412302), we get a palindrome (32733723).

The spelling of 20321421 in words is "twenty million, three hundred twenty-one thousand, four hundred twenty-one".