21442121 has 4 divisors (see below), whose sum is σ = 21476112. Its totient is φ = 21408132.

The previous prime is 21442103. The next prime is 21442133. The reversal of 21442121 is 12124412.

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 a de Polignac number, because none of the positive numbers 2^k-21442121 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21442121.

It is not an unprimeable number, because it can be changed into a prime (21444121) 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, 16031 + ... + 17316.

It is an arithmetic number, because the mean of its divisors is an integer number (5369028).

Almost surely, 2^21442121 is an apocalyptic number.

It is an amenable number.

21442121 is a deficient number, since it is larger than the sum of its proper divisors (33991).

21442121 is an equidigital number, since it uses as much as digits as its factorization.

21442121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33990.

The product of its digits is 128, while the sum is 17.

The square root of 21442121 is about 4630.5637885683. The cubic root of 21442121 is about 277.8151428788.

Adding to 21442121 its reverse (12124412), we get a palindrome (33566533).

The spelling of 21442121 in words is "twenty-one million, four hundred forty-two thousand, one hundred twenty-one".