20421361 has 3 divisors (see below), whose sum is σ = 20425881. Its totient is φ = 20416842.

The previous prime is 20421347. The next prime is 20421367. The reversal of 20421361 is 16312402.

The square root of 20421361 is 4519.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 20421361 - 2⁵ = 20421329 is a prime.

It is a hoax number, since the sum of its digits (19) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20421367) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2260 + ... + 6778.

It is an arithmetic number, because the mean of its divisors is an integer number (6808627).

Almost surely, 2^20421361 is an apocalyptic number.

20421361 is the 4519-th square number.

20421361 is the 2260-th centered octagonal number.

It is an amenable number.

20421361 is a deficient number, since it is larger than the sum of its proper divisors (4520).

20421361 is an frugal number, since it uses more digits than its factorization.

20421361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9038 (or 4519 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

The cubic root of 20421361 is about 273.3347787286.

Adding to 20421361 its reverse (16312402), we get a palindrome (36733763).

It can be divided in two parts, 2042 and 1361, that added together give a triangular number (3403 = T₈₂).

The spelling of 20421361 in words is "twenty million, four hundred twenty-one thousand, three hundred sixty-one".