20657987984 has 10 divisors (see below), whose sum is σ = 40024851750. Its totient is φ = 10328993984.

The previous prime is 20657987969. The next prime is 20657988059. The reversal of 20657987984 is 48978975602.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20657737984 + 250000 = 143728^2 + 500^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20657987984.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645562109 + ... + 645562140.

It is an arithmetic number, because the mean of its divisors is an integer number (4002485175).

Almost surely, 2^20657987984 is an apocalyptic number.

It is an amenable number.

20657987984 is a deficient number, since it is larger than the sum of its proper divisors (19366863766).

20657987984 is a wasteful number, since it uses less digits than its factorization.

20657987984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1291124257 (or 1291124251 counting only the distinct ones).

The product of its (nonzero) digits is 60963840, while the sum is 65.

The spelling of 20657987984 in words is "twenty billion, six hundred fifty-seven million, nine hundred eighty-seven thousand, nine hundred eighty-four".