21766884551 has 4 divisors (see below), whose sum is σ = 21800218872. Its totient is φ = 21733550232.

The previous prime is 21766884539. The next prime is 21766884571. The reversal of 21766884551 is 15548866712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21766884551 - 2³⁰ = 20693142727 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21766884493 and 21766884502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21766884511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16666181 + ... + 16667486.

It is an arithmetic number, because the mean of its divisors is an integer number (5450054718).

Almost surely, 2^21766884551 is an apocalyptic number.

21766884551 is a deficient number, since it is larger than the sum of its proper divisors (33334321).

21766884551 is an equidigital number, since it uses as much as digits as its factorization.

21766884551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33334320.

The product of its digits is 3225600, while the sum is 53.

The spelling of 21766884551 in words is "twenty-one billion, seven hundred sixty-six million, eight hundred eighty-four thousand, five hundred fifty-one".