21156106605205 has 16 divisors (see below), whose sum is σ = 29825671970304. Its totient is φ = 14202700937280.

The previous prime is 21156106605169. The next prime is 21156106605223. The reversal of 21156106605205 is 50250660165112.

It is not a de Polignac number, because 21156106605205 - 2⁷ = 21156106605077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14794479429 + ... + 14794480858.

It is an arithmetic number, because the mean of its divisors is an integer number (1864104498144).

Almost surely, 2^{21156106605205} is an apocalyptic number.

It is an amenable number.

21156106605205 is a deficient number, since it is larger than the sum of its proper divisors (8669565365099).

21156106605205 is a wasteful number, since it uses less digits than its factorization.

21156106605205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29588960316.

The product of its (nonzero) digits is 108000, while the sum is 40.

The spelling of 21156106605205 in words is "twenty-one trillion, one hundred fifty-six billion, one hundred six million, six hundred five thousand, two hundred five".