21809553611 has 2 divisors, whose sum is σ = 21809553612. Its totient is φ = 21809553610.

The previous prime is 21809553599. The next prime is 21809553613. The reversal of 21809553611 is 11635590812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21809553611 - 2⁶ = 21809553547 is a prime.

It is a super-2 number, since 2×21809553611² (a number of 21 digits) contains 22 as substring.

Together with 21809553613, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21809553613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10904776805 + 10904776806.

It is an arithmetic number, because the mean of its divisors is an integer number (10904776806).

Almost surely, 2^21809553611 is an apocalyptic number.

21809553611 is a deficient number, since it is larger than the sum of its proper divisors (1).

21809553611 is an equidigital number, since it uses as much as digits as its factorization.

21809553611 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64800, while the sum is 41.

The spelling of 21809553611 in words is "twenty-one billion, eight hundred nine million, five hundred fifty-three thousand, six hundred eleven".