21102111120509 has 2 divisors, whose sum is σ = 21102111120510. Its totient is φ = 21102111120508.

The previous prime is 21102111120469. The next prime is 21102111120521. The reversal of 21102111120509 is 90502111120112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14941340352409 + 6160770768100 = 3865403^2 + 2482090^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21102111120509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21102111120539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551055560254 + 10551055560255.

It is an arithmetic number, because the mean of its divisors is an integer number (10551055560255).

Almost surely, 2^{21102111120509} is an apocalyptic number.

It is an amenable number.

21102111120509 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102111120509 is an equidigital number, since it uses as much as digits as its factorization.

21102111120509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 360, while the sum is 26.

The spelling of 21102111120509 in words is "twenty-one trillion, one hundred two billion, one hundred eleven million, one hundred twenty thousand, five hundred nine".