21020020022251 has 2 divisors, whose sum is σ = 21020020022252. Its totient is φ = 21020020022250.

The previous prime is 21020020022171. The next prime is 21020020022317. The reversal of 21020020022251 is 15222002002012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21020020022251 - 2¹⁷ = 21020019891179 is a prime.

It is not a weakly prime, because it can be changed into another prime (21020020026251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510010011125 + 10510010011126.

It is an arithmetic number, because the mean of its divisors is an integer number (10510010011126).

Almost surely, 2^{21020020022251} is an apocalyptic number.

21020020022251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020020022251 is an equidigital number, since it uses as much as digits as its factorization.

21020020022251 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 21020020022251 its reverse (15222002002012), we get a palindrome (36242022024263).

The spelling of 21020020022251 in words is "twenty-one trillion, twenty billion, twenty million, twenty-two thousand, two hundred fifty-one".