21216420365166 has 64 divisors (see below), whose sum is σ = 50777937100800. Its totient is φ = 6527666773728.

The previous prime is 21216420365143. The next prime is 21216420365191. The reversal of 21216420365166 is 66156302461212.

21216420365166 is a `hidden beast` number, since 2 + 1 + 2 + 1 + 6 + 420 + 3 + 65 + 166 = 666.

It is a super-2 number, since 2×21216420365166² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

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 31 ways as a sum of consecutive naturals, for example, 8909655 + ... + 11036973.

It is an arithmetic number, because the mean of its divisors is an integer number (793405267200).

Almost surely, 2^{21216420365166} is an apocalyptic number.

21216420365166 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21216420365166 is an abundant number, since it is smaller than the sum of its proper divisors (29561516735634).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21216420365166 is a wasteful number, since it uses less digits than its factorization.

21216420365166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2141550 (or 2141544 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The spelling of 21216420365166 in words is "twenty-one trillion, two hundred sixteen billion, four hundred twenty million, three hundred sixty-five thousand, one hundred sixty-six".