21108001660 has 24 divisors (see below), whose sum is σ = 45078107760. Its totient is φ = 8300095104.

The previous prime is 21108001643. The next prime is 21108001763. The reversal of 21108001660 is 6610080112.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8942889 + ... + 8945248.

It is an arithmetic number, because the mean of its divisors is an integer number (1878254490).

Almost surely, 2^21108001660 is an apocalyptic number.

21108001660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21108001660 is an abundant number, since it is smaller than the sum of its proper divisors (23970106100).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21108001660 is a wasteful number, since it uses less digits than its factorization.

21108001660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17888205 (or 17888203 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 25.

Adding to 21108001660 its reverse (6610080112), we get a palindrome (27718081772).

The spelling of 21108001660 in words is "twenty-one billion, one hundred eight million, one thousand, six hundred sixty".