21551503213 has 2 divisors, whose sum is σ = 21551503214. Its totient is φ = 21551503212.

The previous prime is 21551503159. The next prime is 21551503219. The reversal of 21551503213 is 31230515512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11325642084 + 10225861129 = 106422^2 + 101123^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21551503213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21551503219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10775751606 + 10775751607.

It is an arithmetic number, because the mean of its divisors is an integer number (10775751607).

Almost surely, 2^21551503213 is an apocalyptic number.

It is an amenable number.

21551503213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21551503213 is an equidigital number, since it uses as much as digits as its factorization.

21551503213 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4500, while the sum is 28.

The spelling of 21551503213 in words is "twenty-one billion, five hundred fifty-one million, five hundred three thousand, two hundred thirteen".