20420591 has 2 divisors, whose sum is σ = 20420592. Its totient is φ = 20420590.

The previous prime is 20420579. The next prime is 20420627. The reversal of 20420591 is 19502402.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20420591 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 (20420531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210295 + 10210296.

It is an arithmetic number, because the mean of its divisors is an integer number (10210296).

Almost surely, 2^20420591 is an apocalyptic number.

20420591 is a deficient number, since it is larger than the sum of its proper divisors (1).

20420591 is an equidigital number, since it uses as much as digits as its factorization.

20420591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 20420591 is about 4518.9148033571. The cubic root of 20420591 is about 273.3313432666.

Adding to 20420591 its reverse (19502402), we get a palindrome (39922993).

The spelling of 20420591 in words is "twenty million, four hundred twenty thousand, five hundred ninety-one".