20139869 has 2 divisors, whose sum is σ = 20139870. Its totient is φ = 20139868.

The previous prime is 20139857. The next prime is 20139871. The reversal of 20139869 is 96893102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20025625 + 114244 = 4475^2 + 338^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20139869 is a prime.

It is a super-2 number, since 2×20139869² = 811228646674322, which contains 22 as substring.

Together with 20139871, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20139269) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10069934 + 10069935.

It is an arithmetic number, because the mean of its divisors is an integer number (10069935).

Almost surely, 2^20139869 is an apocalyptic number.

It is an amenable number.

20139869 is a deficient number, since it is larger than the sum of its proper divisors (1).

20139869 is an equidigital number, since it uses as much as digits as its factorization.

20139869 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 20139869 is about 4487.7465391887. The cubic root of 20139869 is about 272.0730637415.

The spelling of 20139869 in words is "twenty million, one hundred thirty-nine thousand, eight hundred sixty-nine".