20506247 has 2 divisors, whose sum is σ = 20506248. Its totient is φ = 20506246.

The previous prime is 20506243. The next prime is 20506249. The reversal of 20506247 is 74260502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20506247 - 2² = 20506243 is a prime.

Together with 20506249, 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 (20506243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10253123 + 10253124.

It is an arithmetic number, because the mean of its divisors is an integer number (10253124).

Almost surely, 2^20506247 is an apocalyptic number.

20506247 is a deficient number, since it is larger than the sum of its proper divisors (1).

20506247 is an equidigital number, since it uses as much as digits as its factorization.

20506247 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3360, while the sum is 26.

The square root of 20506247 is about 4528.3823822641. The cubic root of 20506247 is about 273.7129811010.

Adding to 20506247 its reverse (74260502), we get a palindrome (94766749).

The spelling of 20506247 in words is "twenty million, five hundred six thousand, two hundred forty-seven".