20684819 has 2 divisors, whose sum is σ = 20684820. Its totient is φ = 20684818.

The previous prime is 20684809. The next prime is 20684827. The reversal of 20684819 is 91848602.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20684819 is a prime.

It is a super-2 number, since 2×20684819² = 855723474125522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20684809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10342409 + 10342410.

It is an arithmetic number, because the mean of its divisors is an integer number (10342410).

Almost surely, 2^20684819 is an apocalyptic number.

20684819 is a deficient number, since it is larger than the sum of its proper divisors (1).

20684819 is an equidigital number, since it uses as much as digits as its factorization.

20684819 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 20684819 is about 4548.0566179413. The cubic root of 20684819 is about 274.5051995082.

The spelling of 20684819 in words is "twenty million, six hundred eighty-four thousand, eight hundred nineteen".