21606016505 has 8 divisors (see below), whose sum is σ = 25929820224. Its totient is φ = 17283079600.

The previous prime is 21606016489. The next prime is 21606016507. The reversal of 21606016505 is 50561060612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21606016505 - 2⁴ = 21606016489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21606016507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 160541 + ... + 262650.

It is an arithmetic number, because the mean of its divisors is an integer number (3241227528).

Almost surely, 2^21606016505 is an apocalyptic number.

It is an amenable number.

21606016505 is a deficient number, since it is larger than the sum of its proper divisors (4323803719).

21606016505 is a wasteful number, since it uses less digits than its factorization.

21606016505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 433407.

The product of its (nonzero) digits is 10800, while the sum is 32.

The spelling of 21606016505 in words is "twenty-one billion, six hundred six million, sixteen thousand, five hundred five".