21221604666212 has 6 divisors (see below), whose sum is σ = 37137808165878. Its totient is φ = 10610802333104.

The previous prime is 21221604666211. The next prime is 21221604666247. The reversal of 21221604666212 is 21266640612212.

It can be written as a sum of positive squares in only one way, i.e., 20607459727936 + 614144938276 = 4539544^2 + 783674^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21221604666212.

It is not an unprimeable number, because it can be changed into a prime (21221604666211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2652700583273 + ... + 2652700583280.

It is an arithmetic number, because the mean of its divisors is an integer number (6189634694313).

Almost surely, 2^{21221604666212} is an apocalyptic number.

It is an amenable number.

21221604666212 is a deficient number, since it is larger than the sum of its proper divisors (15916203499666).

21221604666212 is a wasteful number, since it uses less digits than its factorization.

21221604666212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5305401166557 (or 5305401166555 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 41.

The spelling of 21221604666212 in words is "twenty-one trillion, two hundred twenty-one billion, six hundred four million, six hundred sixty-six thousand, two hundred twelve".