21206672705 has 16 divisors (see below), whose sum is σ = 26369460480. Its totient is φ = 16361025408.

The previous prime is 21206672689. The next prime is 21206672713. The reversal of 21206672705 is 50727660212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21206672705 - 2⁴ = 21206672689 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 607292 + ... + 641261.

It is an arithmetic number, because the mean of its divisors is an integer number (1648091280).

Almost surely, 2^21206672705 is an apocalyptic number.

It is an amenable number.

21206672705 is a deficient number, since it is larger than the sum of its proper divisors (5162787775).

21206672705 is a wasteful number, since it uses less digits than its factorization.

21206672705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1248680.

The product of its (nonzero) digits is 70560, while the sum is 38.

The spelling of 21206672705 in words is "twenty-one billion, two hundred six million, six hundred seventy-two thousand, seven hundred five".