21006658908 has 144 divisors (see below), whose sum is σ = 58158487296. Its totient is φ = 6616494720.

The previous prime is 21006658891. The next prime is 21006658927. The reversal of 21006658908 is 80985660012.

21006658908 is a `hidden beast` number, since 2 + 1 + 0 + 0 + 66 + 589 + 0 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1849888 + ... + 1861208.

It is an arithmetic number, because the mean of its divisors is an integer number (403878384).

Almost surely, 2^21006658908 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21006658908, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29079243648).

21006658908 is an abundant number, since it is smaller than the sum of its proper divisors (37151828388).

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

21006658908 is a wasteful number, since it uses less digits than its factorization.

21006658908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11446 (or 11432 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 45.

The spelling of 21006658908 in words is "twenty-one billion, six million, six hundred fifty-eight thousand, nine hundred eight".