21217016620799 has 8 divisors (see below), whose sum is σ = 22139932922880. Its totient is φ = 20294136761976.

The previous prime is 21217016620727. The next prime is 21217016620841. The reversal of 21217016620799 is 99702661071212.

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

It is a cyclic number.

It is not a de Polignac number, because 21217016620799 - 2¹² = 21217016616703 is a prime.

It is a super-2 number, since 2×21217016620799² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21217016620799.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21217016620099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7917779 + ... + 10253060.

It is an arithmetic number, because the mean of its divisors is an integer number (2767491615360).

Almost surely, 2^{21217016620799} is an apocalyptic number.

21217016620799 is a deficient number, since it is larger than the sum of its proper divisors (922916302081).

21217016620799 is a wasteful number, since it uses less digits than its factorization.

21217016620799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18221629.

The product of its (nonzero) digits is 1143072, while the sum is 53.

The spelling of 21217016620799 in words is "twenty-one trillion, two hundred seventeen billion, sixteen million, six hundred twenty thousand, seven hundred ninety-nine".