21211642 has 16 divisors (see below), whose sum is σ = 32785632. Its totient is φ = 10286640.

The previous prime is 21211613. The next prime is 21211643. The reversal of 21211642 is 24611212.

It is not an unprimeable number, because it can be changed into a prime (21211643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12717 + ... + 14287.

It is an arithmetic number, because the mean of its divisors is an integer number (2049102).

Almost surely, 2^21211642 is an apocalyptic number.

21211642 is a deficient number, since it is larger than the sum of its proper divisors (11573990).

21211642 is a wasteful number, since it uses less digits than its factorization.

21211642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1773.

The product of its digits is 192, while the sum is 19.

The square root of 21211642 is about 4605.6098401840. The cubic root of 21211642 is about 276.8161534700.

Adding to 21211642 its reverse (24611212), we get a palindrome (45822854).

The spelling of 21211642 in words is "twenty-one million, two hundred eleven thousand, six hundred forty-two".