20988017721 has 24 divisors (see below), whose sum is σ = 34212447360. Its totient is φ = 12281388000.

The previous prime is 20988017683. The next prime is 20988017723. The reversal of 20988017721 is 12771088902.

It is not a de Polignac number, because 20988017721 - 2¹¹ = 20988015673 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20988017723) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3652305 + ... + 3658046.

It is an arithmetic number, because the mean of its divisors is an integer number (1425518640).

Almost surely, 2^20988017721 is an apocalyptic number.

It is an amenable number.

20988017721 is a deficient number, since it is larger than the sum of its proper divisors (13224429639).

20988017721 is a wasteful number, since it uses less digits than its factorization.

20988017721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7310397 (or 7310394 counting only the distinct ones).

The product of its (nonzero) digits is 112896, while the sum is 45.

The spelling of 20988017721 in words is "twenty billion, nine hundred eighty-eight million, seventeen thousand, seven hundred twenty-one".