20647888921 has 16 divisors (see below), whose sum is σ = 22933500480. Its totient is φ = 18431110080.

The previous prime is 20647888913. The next prime is 20647888939. The reversal of 20647888921 is 12988874602.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 20647888921 - 2³ = 20647888913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20647888721) 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 15 ways as a sum of consecutive naturals, for example, 551035 + ... + 587311.

It is an arithmetic number, because the mean of its divisors is an integer number (1433343780).

Almost surely, 2^20647888921 is an apocalyptic number.

It is an amenable number.

20647888921 is a deficient number, since it is larger than the sum of its proper divisors (2285611559).

20647888921 is a wasteful number, since it uses less digits than its factorization.

20647888921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37224.

The product of its (nonzero) digits is 3096576, while the sum is 55.

The spelling of 20647888921 in words is "twenty billion, six hundred forty-seven million, eight hundred eighty-eight thousand, nine hundred twenty-one".