21221560564666 has 16 divisors (see below), whose sum is σ = 39687074303040. Its totient is φ = 8268140479680.

The previous prime is 21221560564639. The next prime is 21221560564709. The reversal of 21221560564666 is 66646506512212.

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 7 ways as a sum of consecutive naturals, for example, 68901170511 + ... + 68901170818.

It is an arithmetic number, because the mean of its divisors is an integer number (2480442143940).

Almost surely, 2^{21221560564666} is an apocalyptic number.

21221560564666 is a deficient number, since it is larger than the sum of its proper divisors (18465513738374).

21221560564666 is a wasteful number, since it uses less digits than its factorization.

21221560564666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137802341349.

The product of its (nonzero) digits is 6220800, while the sum is 52.

The spelling of 21221560564666 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred sixty million, five hundred sixty-four thousand, six hundred sixty-six".