21211442 has 16 divisors (see below), whose sum is σ = 36493632. Its totient is φ = 9057840.

The previous prime is 21211433. The next prime is 21211481. The reversal of 21211442 is 24411212.

It is a self number, because there is not a number n which added to its sum of digits gives 21211442.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1517 + ... + 6687.

It is an arithmetic number, because the mean of its divisors is an integer number (2280852).

Almost surely, 2^21211442 is an apocalyptic number.

21211442 is a deficient number, since it is larger than the sum of its proper divisors (15282190).

21211442 is a wasteful number, since it uses less digits than its factorization.

21211442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5473.

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

The square root of 21211442 is about 4605.5881274817. The cubic root of 21211442 is about 276.8152834539.

Adding to 21211442 its reverse (24411212), we get a palindrome (45622654).

The spelling of 21211442 in words is "twenty-one million, two hundred eleven thousand, four hundred forty-two".