21106857 has 8 divisors (see below), whose sum is σ = 28163776. Its totient is φ = 14060592.

The previous prime is 21106849. The next prime is 21106859. The reversal of 21106857 is 75860112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21106857 - 2³ = 21106849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21106859) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5868 + ... + 8754.

It is an arithmetic number, because the mean of its divisors is an integer number (3520472).

Almost surely, 2^21106857 is an apocalyptic number.

It is an amenable number.

21106857 is a deficient number, since it is larger than the sum of its proper divisors (7056919).

21106857 is a wasteful number, since it uses less digits than its factorization.

21106857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5327.

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 21106857 is about 4594.2199555528. The cubic root of 21106857 is about 276.3595791127.

Adding to 21106857 its reverse (75860112), we get a palindrome (96966969).

The spelling of 21106857 in words is "twenty-one million, one hundred six thousand, eight hundred fifty-seven".