21166011660 has 48 divisors (see below), whose sum is σ = 59289463296. Its totient is φ = 5641924032.

The previous prime is 21166011641. The next prime is 21166011661. The reversal of 21166011660 is 6611066112.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21166011661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 74739 + ... + 218901.

It is an arithmetic number, because the mean of its divisors is an integer number (1235197152).

Almost surely, 2^21166011660 is an apocalyptic number.

21166011660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21166011660 is an abundant number, since it is smaller than the sum of its proper divisors (38123451636).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21166011660 is a wasteful number, since it uses less digits than its factorization.

21166011660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146622 (or 146620 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

Adding to 21166011660 its reverse (6611066112), we get a palindrome (27777077772).

The spelling of 21166011660 in words is "twenty-one billion, one hundred sixty-six million, eleven thousand, six hundred sixty".