21221406464566 has 256 divisors, whose sum is σ = 42508975841280. Its totient is φ = 7696902528000.

The previous prime is 21221406464549. The next prime is 21221406464603. The reversal of 21221406464566 is 66546460412212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 30711152281 + ... + 30711152971.

It is an arithmetic number, because the mean of its divisors is an integer number (166050686880).

Almost surely, 2^{21221406464566} is an apocalyptic number.

21221406464566 is an abundant number, since it is smaller than the sum of its proper divisors (21287569376714).

21221406464566 is a wasteful number, since it uses less digits than its factorization.

21221406464566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1491.

The product of its (nonzero) digits is 3317760, while the sum is 49.

Adding to 21221406464566 its reverse (66546460412212), we get a palindrome (87767866876778).

The spelling of 21221406464566 in words is "twenty-one trillion, two hundred twenty-one billion, four hundred six million, four hundred sixty-four thousand, five hundred sixty-six".