20421324247 has 2 divisors, whose sum is σ = 20421324248. Its totient is φ = 20421324246.

The previous prime is 20421324223. The next prime is 20421324263. The reversal of 20421324247 is 74242312402.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20421324247 is a prime.

It is a super-2 number, since 2×20421324247² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20421324277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210662123 + 10210662124.

It is an arithmetic number, because the mean of its divisors is an integer number (10210662124).

Almost surely, 2^20421324247 is an apocalyptic number.

20421324247 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421324247 is an equidigital number, since it uses as much as digits as its factorization.

20421324247 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21504, while the sum is 31.

Adding to 20421324247 its reverse (74242312402), we get a palindrome (94663636649).

The spelling of 20421324247 in words is "twenty billion, four hundred twenty-one million, three hundred twenty-four thousand, two hundred forty-seven".