21442321 has 4 divisors (see below), whose sum is σ = 22703652. Its totient is φ = 20180992.

The previous prime is 21442319. The next prime is 21442327. The reversal of 21442321 is 12324412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12680721 + 8761600 = 3561^2 + 2960^2 .

It is a cyclic number.

It is not a de Polignac number, because 21442321 - 2¹ = 21442319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21442327) 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, 630640 + ... + 630673.

It is an arithmetic number, because the mean of its divisors is an integer number (5675913).

Almost surely, 2^21442321 is an apocalyptic number.

It is an amenable number.

21442321 is a deficient number, since it is larger than the sum of its proper divisors (1261331).

21442321 is a wasteful number, since it uses less digits than its factorization.

21442321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1261330.

The product of its digits is 384, while the sum is 19.

The square root of 21442321 is about 4630.5853841604. The cubic root of 21442321 is about 277.8160066437.

Adding to 21442321 its reverse (12324412), we get a palindrome (33766733).

It can be divided in two parts, 2144 and 2321, that added together give a triangular number (4465 = T₉₄).

The spelling of 21442321 in words is "twenty-one million, four hundred forty-two thousand, three hundred twenty-one".