21112857 has 24 divisors (see below), whose sum is σ = 32285760. Its totient is φ = 13258080.

The previous prime is 21112843. The next prime is 21112859. The reversal of 21112857 is 75821112.

It is not a de Polignac number, because 21112857 - 2⁸ = 21112601 is a prime.

It is a super-3 number, since 3×21112857³ (a number of 23 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21112857.

It is not an unprimeable number, because it can be changed into a prime (21112859) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52983 + ... + 53379.

It is an arithmetic number, because the mean of its divisors is an integer number (1345240).

Almost surely, 2^21112857 is an apocalyptic number.

It is an amenable number.

21112857 is a deficient number, since it is larger than the sum of its proper divisors (11172903).

21112857 is a wasteful number, since it uses less digits than its factorization.

21112857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 733 (or 730 counting only the distinct ones).

The product of its digits is 1120, while the sum is 27.

The square root of 21112857 is about 4594.8729035742. The cubic root of 21112857 is about 276.3857633425.

Adding to 21112857 its reverse (75821112), we get a palindrome (96933969).

The spelling of 21112857 in words is "twenty-one million, one hundred twelve thousand, eight hundred fifty-seven".