20687931888 has 80 divisors (see below), whose sum is σ = 57680537376. Its totient is φ = 6351621120.

The previous prime is 20687931863. The next prime is 20687931893. The reversal of 20687931888 is 88813978602.

It is a Cunningham number, because it is equal to 143833²-1.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 251706 + ... + 323622.

Almost surely, 2^20687931888 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20687931888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28840268688).

20687931888 is an abundant number, since it is smaller than the sum of its proper divisors (36992605488).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20687931888 is a wasteful number, since it uses less digits than its factorization.

20687931888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72402 (or 72396 counting only the distinct ones).

The product of its (nonzero) digits is 9289728, while the sum is 60.

The spelling of 20687931888 in words is "twenty billion, six hundred eighty-seven million, nine hundred thirty-one thousand, eight hundred eighty-eight".