21206921917066 has 16 divisors (see below), whose sum is σ = 32909077787040. Its totient is φ = 10237268991600.

The previous prime is 21206921916911. The next prime is 21206921917117. The reversal of 21206921917066 is 66071912960212.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8838156 + ... + 10978471.

It is an arithmetic number, because the mean of its divisors is an integer number (2056817361690).

Almost surely, 2^{21206921917066} is an apocalyptic number.

21206921917066 is a deficient number, since it is larger than the sum of its proper divisors (11702155869974).

21206921917066 is a wasteful number, since it uses less digits than its factorization.

21206921917066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19835109.

The product of its (nonzero) digits is 979776, while the sum is 52.

The spelling of 21206921917066 in words is "twenty-one trillion, two hundred six billion, nine hundred twenty-one million, nine hundred seventeen thousand, sixty-six".