21111427 has 4 divisors (see below), whose sum is σ = 21168400. Its totient is φ = 21054456.

The previous prime is 21111397. The next prime is 21111457. The reversal of 21111427 is 72411112.

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

It is an interprime number because it is at equal distance from previous prime (21111397) and next prime (21111457).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111457) 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, 27927 + ... + 28672.

It is an arithmetic number, because the mean of its divisors is an integer number (5292100).

Almost surely, 2^21111427 is an apocalyptic number.

21111427 is a deficient number, since it is larger than the sum of its proper divisors (56973).

21111427 is an equidigital number, since it uses as much as digits as its factorization.

21111427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56972.

The product of its digits is 112, while the sum is 19.

The square root of 21111427 is about 4594.7172927178. The cubic root of 21111427 is about 276.3795232181.

Adding to 21111427 its reverse (72411112), we get a palindrome (93522539).

The spelling of 21111427 in words is "twenty-one million, one hundred eleven thousand, four hundred twenty-seven".