21811113 has 20 divisors (see below), whose sum is σ = 33076560. Its totient is φ = 14320152.

The previous prime is 21811109. The next prime is 21811117. The reversal of 21811113 is 31111812.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21811109) and next prime (21811117).

It is not a de Polignac number, because 21811113 - 2² = 21811109 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21811117) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3418 + ... + 7436.

It is an arithmetic number, because the mean of its divisors is an integer number (1653828).

Almost surely, 2^21811113 is an apocalyptic number.

It is an amenable number.

21811113 is a deficient number, since it is larger than the sum of its proper divisors (11265447).

21811113 is an equidigital number, since it uses as much as digits as its factorization.

21811113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4098 (or 4089 counting only the distinct ones).

The product of its digits is 48, while the sum is 18.

The square root of 21811113 is about 4670.2369318911. The cubic root of 21811113 is about 279.3997045853.

Adding to 21811113 its reverse (31111812), we get a palindrome (52922925).

The spelling of 21811113 in words is "twenty-one million, eight hundred eleven thousand, one hundred thirteen".