21100347878666 has 32 divisors (see below), whose sum is σ = 36213004058880. Its totient is φ = 9032763309696.

The previous prime is 21100347878647. The next prime is 21100347878681. The reversal of 21100347878666 is 66687874300112.

It is a happy number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 147614606 + ... + 147757478.

It is an arithmetic number, because the mean of its divisors is an integer number (1131656376840).

Almost surely, 2^{21100347878666} is an apocalyptic number.

21100347878666 is a deficient number, since it is larger than the sum of its proper divisors (15112656180214).

21100347878666 is a wasteful number, since it uses less digits than its factorization.

21100347878666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154758.

The product of its (nonzero) digits is 16257024, while the sum is 59.

The spelling of 21100347878666 in words is "twenty-one trillion, one hundred billion, three hundred forty-seven million, eight hundred seventy-eight thousand, six hundred sixty-six".