21161603555 has 8 divisors (see below), whose sum is σ = 25395407712. Its totient is φ = 16928293888.

The previous prime is 21161603531. The next prime is 21161603611. The reversal of 21161603555 is 55530616112.

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 21161603555 - 2¹⁰ = 21161602531 is a prime.

It is a Duffinian number.

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, 21854 + ... + 206883.

It is an arithmetic number, because the mean of its divisors is an integer number (3174425964).

Almost surely, 2^21161603555 is an apocalyptic number.

21161603555 is a deficient number, since it is larger than the sum of its proper divisors (4233804157).

21161603555 is a wasteful number, since it uses less digits than its factorization.

21161603555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247245.

The product of its (nonzero) digits is 27000, while the sum is 35.

The spelling of 21161603555 in words is "twenty-one billion, one hundred sixty-one million, six hundred three thousand, five hundred fifty-five".