20421347 has 2 divisors, whose sum is σ = 20421348. Its totient is φ = 20421346.

The previous prime is 20421337. The next prime is 20421367. The reversal of 20421347 is 74312402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20421347 - 2¹⁸ = 20159203 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20421337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210673 + 10210674.

It is an arithmetic number, because the mean of its divisors is an integer number (10210674).

Almost surely, 2^20421347 is an apocalyptic number.

20421347 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421347 is an equidigital number, since it uses as much as digits as its factorization.

20421347 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 20421347 is about 4518.9984509845. The cubic root of 20421347 is about 273.3347162664.

Adding to 20421347 its reverse (74312402), we get a palindrome (94733749).

The spelling of 20421347 in words is "twenty million, four hundred twenty-one thousand, three hundred forty-seven".