21211131 has 4 divisors (see below), whose sum is σ = 28281512. Its totient is φ = 14140752.

The previous prime is 21211109. The next prime is 21211139. The reversal of 21211131 is 13111212.

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

It is not a de Polignac number, because 21211131 - 2⁹ = 21210619 is a prime.

It is a super-2 number, since 2×21211131² = 899824156598322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21211139) 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, 3535186 + ... + 3535191.

It is an arithmetic number, because the mean of its divisors is an integer number (7070378).

Almost surely, 2^21211131 is an apocalyptic number.

21211131 is a deficient number, since it is larger than the sum of its proper divisors (7070381).

21211131 is an equidigital number, since it uses as much as digits as its factorization.

21211131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7070380.

The product of its digits is 12, while the sum is 12.

The square root of 21211131 is about 4605.5543640261. The cubic root of 21211131 is about 276.8139305682.

Adding to 21211131 its reverse (13111212), we get a palindrome (34322343).

The spelling of 21211131 in words is "twenty-one million, two hundred eleven thousand, one hundred thirty-one".