21105072666 has 32 divisors (see below), whose sum is σ = 47009030400. Its totient is φ = 7018693920.

The previous prime is 21105072661. The next prime is 21105072679. The reversal of 21105072666 is 66627050112.

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 21105072666.

It is not an unprimeable number, because it can be changed into a prime (21105072661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 430131 + ... + 476678.

It is an arithmetic number, because the mean of its divisors is an integer number (1469032200).

Almost surely, 2^21105072666 is an apocalyptic number.

21105072666 is an abundant number, since it is smaller than the sum of its proper divisors (25903957734).

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

21105072666 is a wasteful number, since it uses less digits than its factorization.

21105072666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 907251 (or 907245 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The spelling of 21105072666 in words is "twenty-one billion, one hundred five million, seventy-two thousand, six hundred sixty-six".