21855186607 has 4 divisors (see below), whose sum is σ = 21869945136. Its totient is φ = 21840428080.

The previous prime is 21855186421. The next prime is 21855186623. The reversal of 21855186607 is 70668155812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21855186607 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855186907) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7377043 + ... + 7380004.

It is an arithmetic number, because the mean of its divisors is an integer number (5467486284).

Almost surely, 2^21855186607 is an apocalyptic number.

21855186607 is a deficient number, since it is larger than the sum of its proper divisors (14758529).

21855186607 is a wasteful number, since it uses less digits than its factorization.

21855186607 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14758528.

The product of its (nonzero) digits is 806400, while the sum is 49.

The spelling of 21855186607 in words is "twenty-one billion, eight hundred fifty-five million, one hundred eighty-six thousand, six hundred seven".