20388391 has 2 divisors, whose sum is σ = 20388392. Its totient is φ = 20388390.

The previous prime is 20388371. The next prime is 20388397. The reversal of 20388391 is 19388302.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20388391 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20388397) 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, 10194195 + 10194196.

It is an arithmetic number, because the mean of its divisors is an integer number (10194196).

Almost surely, 2^20388391 is an apocalyptic number.

20388391 is a deficient number, since it is larger than the sum of its proper divisors (1).

20388391 is an equidigital number, since it uses as much as digits as its factorization.

20388391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 20388391 is about 4515.3505954688. The cubic root of 20388391 is about 273.1876011099.

The spelling of 20388391 in words is "twenty million, three hundred eighty-eight thousand, three hundred ninety-one".