21606403210665 has 64 divisors (see below), whose sum is σ = 45050817240576. Its totient is φ = 8581108027392.

The previous prime is 21606403210627. The next prime is 21606403210673. The reversal of 21606403210665 is 56601230460612.

It is not a de Polignac number, because 21606403210665 - 2⁸ = 21606403210409 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 465531702 + ... + 465578111.

It is an arithmetic number, because the mean of its divisors is an integer number (703919019384).

Almost surely, 2^{21606403210665} is an apocalyptic number.

It is an amenable number.

21606403210665 is an abundant number, since it is smaller than the sum of its proper divisors (23444414029911).

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

21606403210665 is a wasteful number, since it uses less digits than its factorization.

21606403210665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 931109858.

The product of its (nonzero) digits is 311040, while the sum is 42.

The spelling of 21606403210665 in words is "twenty-one trillion, six hundred six billion, four hundred three million, two hundred ten thousand, six hundred sixty-five".