21167857 has 2 divisors, whose sum is σ = 21167858. Its totient is φ = 21167856.

The previous prime is 21167851. The next prime is 21167863. The reversal of 21167857 is 75876112.

It is a balanced prime because it is at equal distance from previous prime (21167851) and next prime (21167863).

It can be written as a sum of positive squares in only one way, i.e., 20421361 + 746496 = 4519^2 + 864^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21167857 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21167851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10583928 + 10583929.

It is an arithmetic number, because the mean of its divisors is an integer number (10583929).

Almost surely, 2^21167857 is an apocalyptic number.

It is an amenable number.

21167857 is a deficient number, since it is larger than the sum of its proper divisors (1).

21167857 is an equidigital number, since it uses as much as digits as its factorization.

21167857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23520, while the sum is 37.

The square root of 21167857 is about 4600.8539424763. The cubic root of 21167857 is about 276.6255546079.

The spelling of 21167857 in words is "twenty-one million, one hundred sixty-seven thousand, eight hundred fifty-seven".