20909547905 has 8 divisors (see below), whose sum is σ = 25245393792. Its totient is φ = 16625014128.

The previous prime is 20909547793. The next prime is 20909547913. The reversal of 20909547905 is 50974590902.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20909547905 - 2²⁰ = 20908499329 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12827129 + ... + 12828758.

It is an arithmetic number, because the mean of its divisors is an integer number (3155674224).

Almost surely, 2^20909547905 is an apocalyptic number.

It is an amenable number.

20909547905 is a deficient number, since it is larger than the sum of its proper divisors (4335845887).

20909547905 is a wasteful number, since it uses less digits than its factorization.

20909547905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25656055.

The product of its (nonzero) digits is 1020600, while the sum is 50.

The spelling of 20909547905 in words is "twenty billion, nine hundred nine million, five hundred forty-seven thousand, nine hundred five".