21510853261 has 2 divisors, whose sum is σ = 21510853262. Its totient is φ = 21510853260.

The previous prime is 21510853241. The next prime is 21510853267. The reversal of 21510853261 is 16235801512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13719436900 + 7791416361 = 117130^2 + 88269^2 .

It is a cyclic number.

It is not a de Polignac number, because 21510853261 - 2²³ = 21502464653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21510853267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10755426630 + 10755426631.

It is an arithmetic number, because the mean of its divisors is an integer number (10755426631).

Almost surely, 2^21510853261 is an apocalyptic number.

It is an amenable number.

21510853261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21510853261 is an equidigital number, since it uses as much as digits as its factorization.

21510853261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14400, while the sum is 34.

The spelling of 21510853261 in words is "twenty-one billion, five hundred ten million, eight hundred fifty-three thousand, two hundred sixty-one".