21117766356646 has 16 divisors (see below), whose sum is σ = 31693179619584. Its totient is φ = 10553374594504.

The previous prime is 21117766356521. The next prime is 21117766356649. The reversal of 21117766356646 is 64665366771112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21117766356649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29198631 + ... + 29913133.

It is an arithmetic number, because the mean of its divisors is an integer number (1980823726224).

Almost surely, 2^{21117766356646} is an apocalyptic number.

21117766356646 is a deficient number, since it is larger than the sum of its proper divisors (10575413262938).

21117766356646 is a wasteful number, since it uses less digits than its factorization.

21117766356646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722195.

The product of its digits is 45722880, while the sum is 61.

The spelling of 21117766356646 in words is "twenty-one trillion, one hundred seventeen billion, seven hundred sixty-six million, three hundred fifty-six thousand, six hundred forty-six".