20390197 has 2 divisors, whose sum is σ = 20390198. Its totient is φ = 20390196.

The previous prime is 20390147. The next prime is 20390207. The reversal of 20390197 is 79109302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14070001 + 6320196 = 3751^2 + 2514^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20390197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20390147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10195098 + 10195099.

It is an arithmetic number, because the mean of its divisors is an integer number (10195099).

Almost surely, 2^20390197 is an apocalyptic number.

It is an amenable number.

20390197 is a deficient number, since it is larger than the sum of its proper divisors (1).

20390197 is an equidigital number, since it uses as much as digits as its factorization.

20390197 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3402, while the sum is 31.

The square root of 20390197 is about 4515.5505755113. The cubic root of 20390197 is about 273.1956671746.

Adding to 20390197 its reverse (79109302), we get a palindrome (99499499).

The spelling of 20390197 in words is "twenty million, three hundred ninety thousand, one hundred ninety-seven".