16820857 has 2 divisors, whose sum is σ = 16820858. Its totient is φ = 16820856.

The previous prime is 16820849. The next prime is 16820861. The reversal of 16820857 is 75802861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16088121 + 732736 = 4011^2 + 856^2 .

It is an emirp because it is prime and its reverse (75802861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16820857 - 2³ = 16820849 is a prime.

It is not a weakly prime, because it can be changed into another prime (16820897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8410428 + 8410429.

It is an arithmetic number, because the mean of its divisors is an integer number (8410429).

Almost surely, 2^16820857 is an apocalyptic number.

It is an amenable number.

16820857 is a deficient number, since it is larger than the sum of its proper divisors (1).

16820857 is an equidigital number, since it uses as much as digits as its factorization.

16820857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 16820857 is about 4101.3238106738. The cubic root of 16820857 is about 256.2217774192.

It can be divided in two parts, 168 and 20857, that added together give a square (21025 = 145²).

The spelling of 16820857 in words is "sixteen million, eight hundred twenty thousand, eight hundred fifty-seven".