19995851 has 2 divisors, whose sum is σ = 19995852. Its totient is φ = 19995850.

The previous prime is 19995797. The next prime is 19995853. The reversal of 19995851 is 15859991.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19995851 is a prime.

Together with 19995853, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 19995796 and 19995805.

It is not a weakly prime, because it can be changed into another prime (19995853) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9997925 + 9997926.

It is an arithmetic number, because the mean of its divisors is an integer number (9997926).

Almost surely, 2^19995851 is an apocalyptic number.

19995851 is a deficient number, since it is larger than the sum of its proper divisors (1).

19995851 is an equidigital number, since it uses as much as digits as its factorization.

19995851 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145800, while the sum is 47.

The square root of 19995851 is about 4471.6720586376. The cubic root of 19995851 is about 271.4229901636.

The spelling of 19995851 in words is "nineteen million, nine hundred ninety-five thousand, eight hundred fifty-one".