21311020253 has 2 divisors, whose sum is σ = 21311020254.
Its totient is φ = 21311020252.
The previous prime is 21311020229. The next prime is 21311020309. The reversal of 21311020253 is 35202011312.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 18397395769 + 2913624484 = 135637^2 + 53978^2
It is a cyclic number.
It is not a de Polignac number, because 21311020253 - 26 = 21311020189 is a prime.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (21311029253) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655510126 + 10655510127.
It is an arithmetic number, because the mean of its divisors is an integer number (10655510127).
Almost surely, 221311020253 is an apocalyptic number.
It is an amenable number.
21311020253 is a deficient number, since it is larger than the sum of its proper divisors (1).
21311020253 is an equidigital number, since it uses as much as digits as its factorization.
21311020253 is an odious number, because the sum of its binary digits is odd.
The product of its (nonzero) digits is 360, while the sum is 20.
Adding to 21311020253 its reverse (35202011312), we get a palindrome (56513031565).
The spelling of 21311020253 in words is "twenty-one billion, three hundred eleven million, twenty thousand, two hundred fifty-three".