21187503261866 has 16 divisors (see below), whose sum is σ = 32929263555840. Its totient is φ = 10212239928240.

The previous prime is 21187503261833. The next prime is 21187503261877. The reversal of 21187503261866 is 66816230578112.

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, 289425986 + ... + 289499181.

It is an arithmetic number, because the mean of its divisors is an integer number (2058078972240).

Almost surely, 2^{21187503261866} is an apocalyptic number.

21187503261866 is a deficient number, since it is larger than the sum of its proper divisors (11741760293974).

21187503261866 is a wasteful number, since it uses less digits than its factorization.

21187503261866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 578925829.

The product of its (nonzero) digits is 5806080, while the sum is 56.

The spelling of 21187503261866 in words is "twenty-one trillion, one hundred eighty-seven billion, five hundred three million, two hundred sixty-one thousand, eight hundred sixty-six".