19806851 has 2 divisors, whose sum is σ = 19806852. Its totient is φ = 19806850.

The previous prime is 19806833. The next prime is 19806859. The reversal of 19806851 is 15860891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19806851 - 2¹⁴ = 19790467 is a prime.

It is a super-2 number, since 2×19806851² = 784622693072402, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (19806859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9903425 + 9903426.

It is an arithmetic number, because the mean of its divisors is an integer number (9903426).

Almost surely, 2^19806851 is an apocalyptic number.

19806851 is a deficient number, since it is larger than the sum of its proper divisors (1).

19806851 is an equidigital number, since it uses as much as digits as its factorization.

19806851 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 38.

The square root of 19806851 is about 4450.4888495535. The cubic root of 19806851 is about 270.5651217914.

The spelling of 19806851 in words is "nineteen million, eight hundred six thousand, eight hundred fifty-one".