21208813555 has 8 divisors (see below), whose sum is σ = 26790080400. Its totient is φ = 16074048096.

The previous prime is 21208813541. The next prime is 21208813601. The reversal of 21208813555 is 55531880212.

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 21208813555 - 2⁵ = 21208813523 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 111625240 + ... + 111625429.

It is an arithmetic number, because the mean of its divisors is an integer number (3348760050).

Almost surely, 2^21208813555 is an apocalyptic number.

21208813555 is a deficient number, since it is larger than the sum of its proper divisors (5581266845).

21208813555 is a wasteful number, since it uses less digits than its factorization.

21208813555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223250693.

The product of its (nonzero) digits is 96000, while the sum is 40.

The spelling of 21208813555 in words is "twenty-one billion, two hundred eight million, eight hundred thirteen thousand, five hundred fifty-five".