21181011966 has 24 divisors (see below), whose sum is σ = 45895299840. Its totient is φ = 7059859296.

The previous prime is 21181011961. The next prime is 21181011991. The reversal of 21181011966 is 66911018112.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21181011966.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21181011961) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 322450 + ... + 382538.

It is an arithmetic number, because the mean of its divisors is an integer number (1912304160).

Almost surely, 2^21181011966 is an apocalyptic number.

21181011966 is an abundant number, since it is smaller than the sum of its proper divisors (24714287874).

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

21181011966 is a wasteful number, since it uses less digits than its factorization.

21181011966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79680 (or 79677 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 36.

The spelling of 21181011966 in words is "twenty-one billion, one hundred eighty-one million, eleven thousand, nine hundred sixty-six".