21166616571 has 32 divisors (see below), whose sum is σ = 30176509440. Its totient is φ = 13165092864.

The previous prime is 21166616557. The next prime is 21166616593. The reversal of 21166616571 is 17561666112.

It is a happy number.

It is not a de Polignac number, because 21166616571 - 2⁵ = 21166616539 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21166616501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2276985 + ... + 2286261.

It is an arithmetic number, because the mean of its divisors is an integer number (943015920).

Almost surely, 2^21166616571 is an apocalyptic number.

21166616571 is a deficient number, since it is larger than the sum of its proper divisors (9009892869).

21166616571 is a wasteful number, since it uses less digits than its factorization.

21166616571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10115.

The product of its digits is 90720, while the sum is 42.

The spelling of 21166616571 in words is "twenty-one billion, one hundred sixty-six million, six hundred sixteen thousand, five hundred seventy-one".