21766066351 has 4 divisors (see below), whose sum is σ = 21778924552. Its totient is φ = 21753208152.

The previous prime is 21766066349. The next prime is 21766066381. The reversal of 21766066351 is 15366066712.

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 21766066351 - 2¹ = 21766066349 is a prime.

It is a super-2 number, since 2×21766066351² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21766066298 and 21766066307.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21766066381) 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, 6426561 + ... + 6429946.

It is an arithmetic number, because the mean of its divisors is an integer number (5444731138).

Almost surely, 2^21766066351 is an apocalyptic number.

21766066351 is a deficient number, since it is larger than the sum of its proper divisors (12858201).

21766066351 is a wasteful number, since it uses less digits than its factorization.

21766066351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12858200.

The product of its (nonzero) digits is 272160, while the sum is 43.

The spelling of 21766066351 in words is "twenty-one billion, seven hundred sixty-six million, sixty-six thousand, three hundred fifty-one".