21112757 has 4 divisors (see below), whose sum is σ = 21123180. Its totient is φ = 21102336.

The previous prime is 21112753. The next prime is 21112769. The reversal of 21112757 is 75721112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 19838116 + 1274641 = 4454^2 + 1129^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112757 - 2² = 21112753 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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1082 + ... + 6587.

It is an arithmetic number, because the mean of its divisors is an integer number (5280795).

Almost surely, 2^21112757 is an apocalyptic number.

It is an amenable number.

21112757 is a deficient number, since it is larger than the sum of its proper divisors (10423).

21112757 is an equidigital number, since it uses as much as digits as its factorization.

21112757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10422.

The product of its digits is 980, while the sum is 26.

The square root of 21112757 is about 4594.8620218675. The cubic root of 21112757 is about 276.3853269793.

Adding to 21112757 its reverse (75721112), we get a palindrome (96833869).

The spelling of 21112757 in words is "twenty-one million, one hundred twelve thousand, seven hundred fifty-seven".