21165452666 has 8 divisors (see below), whose sum is σ = 31759820820. Its totient is φ = 10578845728.

The previous prime is 21165452663. The next prime is 21165452701. The reversal of 21165452666 is 66625456112.

It can be written as a sum of positive squares in 2 ways, for example, as 20917547641 + 247905025 = 144629^2 + 15745^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21165452663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1933481 + ... + 1944396.

Almost surely, 2^21165452666 is an apocalyptic number.

21165452666 is a deficient number, since it is larger than the sum of its proper divisors (10594368154).

21165452666 is a wasteful number, since it uses less digits than its factorization.

21165452666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3880608.

The product of its digits is 518400, while the sum is 44.

The spelling of 21165452666 in words is "twenty-one billion, one hundred sixty-five million, four hundred fifty-two thousand, six hundred sixty-six".