19782109 has 2 divisors, whose sum is σ = 19782110. Its totient is φ = 19782108.

The previous prime is 19782079. The next prime is 19782121. The reversal of 19782109 is 90128791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17388900 + 2393209 = 4170^2 + 1547^2 .

It is an emirp because it is prime and its reverse (90128791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19782109 - 2⁷ = 19781981 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19782199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9891054 + 9891055.

It is an arithmetic number, because the mean of its divisors is an integer number (9891055).

Almost surely, 2^19782109 is an apocalyptic number.

It is an amenable number.

19782109 is a deficient number, since it is larger than the sum of its proper divisors (1).

19782109 is an equidigital number, since it uses as much as digits as its factorization.

19782109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 19782109 is about 4447.7082862976. The cubic root of 19782109 is about 270.4524148024.

It can be divided in two parts, 19782 and 109, that added together give a palindrome (19891).

The spelling of 19782109 in words is "nineteen million, seven hundred eighty-two thousand, one hundred nine".