21155541806 has 12 divisors (see below), whose sum is σ = 36267576072. Its totient is φ = 9066427536.

The previous prime is 21155541791. The next prime is 21155541859. The reversal of 21155541806 is 60814555112.

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21155541806.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 524786 + ... + 563658.

It is an arithmetic number, because the mean of its divisors is an integer number (3022298006).

Almost surely, 2^21155541806 is an apocalyptic number.

21155541806 is a deficient number, since it is larger than the sum of its proper divisors (15112034266).

21155541806 is an frugal number, since it uses more digits than its factorization.

21155541806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77755 (or 38882 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 38.

The spelling of 21155541806 in words is "twenty-one billion, one hundred fifty-five million, five hundred forty-one thousand, eight hundred six".