20420102251 has 2 divisors, whose sum is σ = 20420102252. Its totient is φ = 20420102250.

The previous prime is 20420102207. The next prime is 20420102281. The reversal of 20420102251 is 15220102402.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20420102251 - 2⁹ = 20420101739 is a prime.

It is not a weakly prime, because it can be changed into another prime (20420102281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210051125 + 10210051126.

It is an arithmetic number, because the mean of its divisors is an integer number (10210051126).

Almost surely, 2^20420102251 is an apocalyptic number.

20420102251 is a deficient number, since it is larger than the sum of its proper divisors (1).

20420102251 is an equidigital number, since it uses as much as digits as its factorization.

20420102251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 320, while the sum is 19.

Adding to 20420102251 its reverse (15220102402), we get a palindrome (35640204653).

The spelling of 20420102251 in words is "twenty billion, four hundred twenty million, one hundred two thousand, two hundred fifty-one".