20857213 has 8 divisors (see below), whose sum is σ = 22523256. Its totient is φ = 19200000.

The previous prime is 20857211. The next prime is 20857217. The reversal of 20857213 is 31275802.

It can be written as a sum of positive squares in 4 ways, for example, as 1258884 + 19598329 = 1122^2 + 4427^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20857213 - 2¹ = 20857211 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 (20857211) 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, 3213 + ... + 7213.

It is an arithmetic number, because the mean of its divisors is an integer number (2815407).

Almost surely, 2^20857213 is an apocalyptic number.

It is an amenable number.

20857213 is a deficient number, since it is larger than the sum of its proper divisors (1666043).

20857213 is a wasteful number, since it uses less digits than its factorization.

20857213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4415.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 20857213 is about 4566.9697831275. The cubic root of 20857213 is about 275.2656958280.

The spelling of 20857213 in words is "twenty million, eight hundred fifty-seven thousand, two hundred thirteen".