21855005187 has 16 divisors (see below), whose sum is σ = 29855323680. Its totient is φ = 14212454400.

The previous prime is 21855005147. The next prime is 21855005213. The reversal of 21855005187 is 78150055812.

It is not a de Polignac number, because 21855005187 - 2¹¹ = 21855003139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21855005147) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1311387 + ... + 1327947.

It is an arithmetic number, because the mean of its divisors is an integer number (1865957730).

Almost surely, 2^21855005187 is an apocalyptic number.

21855005187 is a deficient number, since it is larger than the sum of its proper divisors (8000318493).

21855005187 is a wasteful number, since it uses less digits than its factorization.

21855005187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27334.

The product of its (nonzero) digits is 112000, while the sum is 42.

The spelling of 21855005187 in words is "twenty-one billion, eight hundred fifty-five million, five thousand, one hundred eighty-seven".