21112751 has 4 divisors (see below), whose sum is σ = 23032104. Its totient is φ = 19193400.

The previous prime is 21112739. The next prime is 21112753. The reversal of 21112751 is 15721112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21112751 - 2¹⁴ = 21096367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112753) 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 3 ways as a sum of consecutive naturals, for example, 959660 + ... + 959681.

It is an arithmetic number, because the mean of its divisors is an integer number (5758026).

Almost surely, 2^21112751 is an apocalyptic number.

21112751 is a deficient number, since it is larger than the sum of its proper divisors (1919353).

21112751 is a wasteful number, since it uses less digits than its factorization.

21112751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1919352.

The product of its digits is 140, while the sum is 20.

The square root of 21112751 is about 4594.8613689642. The cubic root of 21112751 is about 276.3853007975.

Adding to 21112751 its reverse (15721112), we get a palindrome (36833863).

The spelling of 21112751 in words is "twenty-one million, one hundred twelve thousand, seven hundred fifty-one".