21089997606 has 48 divisors (see below), whose sum is σ = 44571294144. Its totient is φ = 6651853488.

The previous prime is 21089997589. The next prime is 21089997619. The reversal of 21089997606 is 60679998012.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1907065 + ... + 1918091.

It is an arithmetic number, because the mean of its divisors is an integer number (928568628).

Almost surely, 2^21089997606 is an apocalyptic number.

21089997606 is an abundant number, since it is smaller than the sum of its proper divisors (23481296538).

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

21089997606 is a wasteful number, since it uses less digits than its factorization.

21089997606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11953 (or 11934 counting only the distinct ones).

The product of its (nonzero) digits is 2939328, while the sum is 57.

It can be divided in two parts, 210899 and 97606, that added together give a triangular number (308505 = T₇₈₅).

The spelling of 21089997606 in words is "twenty-one billion, eighty-nine million, nine hundred ninety-seven thousand, six hundred six".