20646649971 has 24 divisors (see below), whose sum is σ = 29926144560. Its totient is φ = 13716864000.

The previous prime is 20646649939. The next prime is 20646649981. The reversal of 20646649971 is 17994664602.

It is a happy number.

20646649971 is a `hidden beast` number, since 20 + 6 + 4 + 66 + 499 + 71 = 666.

It is not a de Polignac number, because 20646649971 - 2⁵ = 20646649939 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20646649901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7369771 + ... + 7372571.

It is an arithmetic number, because the mean of its divisors is an integer number (1246922690).

Almost surely, 2^20646649971 is an apocalyptic number.

20646649971 is a deficient number, since it is larger than the sum of its proper divisors (9279494589).

20646649971 is a wasteful number, since it uses less digits than its factorization.

20646649971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5347 (or 5344 counting only the distinct ones).

The product of its (nonzero) digits is 3919104, while the sum is 54.

The spelling of 20646649971 in words is "twenty billion, six hundred forty-six million, six hundred forty-nine thousand, nine hundred seventy-one".