21766565047 has 2 divisors, whose sum is σ = 21766565048. Its totient is φ = 21766565046.

The previous prime is 21766565011. The next prime is 21766565057. The reversal of 21766565047 is 74056566712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21766565047 - 2¹¹ = 21766562999 is a prime.

It is a super-2 number, since 2×21766565047² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21766565057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10883282523 + 10883282524.

It is an arithmetic number, because the mean of its divisors is an integer number (10883282524).

Almost surely, 2^21766565047 is an apocalyptic number.

21766565047 is a deficient number, since it is larger than the sum of its proper divisors (1).

21766565047 is an equidigital number, since it uses as much as digits as its factorization.

21766565047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2116800, while the sum is 49.

The spelling of 21766565047 in words is "twenty-one billion, seven hundred sixty-six million, five hundred sixty-five thousand, forty-seven".