20928551287 has 6 divisors (see below), whose sum is σ = 23918781768. Its totient is φ = 17938430172.

The previous prime is 20928551261. The next prime is 20928551291. The reversal of 20928551287 is 78215582902.

It is not a de Polignac number, because 20928551287 - 2⁷ = 20928551159 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20928551287.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20928551257) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 355414 + ... + 410092.

It is an arithmetic number, because the mean of its divisors is an integer number (3986463628).

Almost surely, 2^20928551287 is an apocalyptic number.

20928551287 is a deficient number, since it is larger than the sum of its proper divisors (2990230481).

20928551287 is an frugal number, since it uses more digits than its factorization.

20928551287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109365 (or 54686 counting only the distinct ones).

The product of its (nonzero) digits is 806400, while the sum is 49.

The spelling of 20928551287 in words is "twenty billion, nine hundred twenty-eight million, five hundred fifty-one thousand, two hundred eighty-seven".