21311143 has 16 divisors (see below), whose sum is σ = 25623360. Its totient is φ = 17337600.

The previous prime is 21311137. The next prime is 21311161. The reversal of 21311143 is 34111312.

It is not a de Polignac number, because 21311143 - 2⁵ = 21311111 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11523 + ... + 13243.

It is an arithmetic number, because the mean of its divisors is an integer number (1601460).

Almost surely, 2^21311143 is an apocalyptic number.

21311143 is a deficient number, since it is larger than the sum of its proper divisors (4312217).

21311143 is a wasteful number, since it uses less digits than its factorization.

21311143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1818.

The product of its digits is 72, while the sum is 16.

The square root of 21311143 is about 4616.3993544753. The cubic root of 21311143 is about 277.2483143931.

Adding to 21311143 its reverse (34111312), we get a palindrome (55422455).

The spelling of 21311143 in words is "twenty-one million, three hundred eleven thousand, one hundred forty-three".