21020187680 has 48 divisors (see below), whose sum is σ = 50099707224. Its totient is φ = 8333660160.

The previous prime is 21020187679. The next prime is 21020187709. The reversal of 21020187680 is 8678102012.

It can be written as a sum of positive squares in 4 ways, for example, as 7898943376 + 13121244304 = 88876^2 + 114548^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21020187680.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 563231 + ... + 599390.

Almost surely, 2^21020187680 is an apocalyptic number.

21020187680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020187680 is an abundant number, since it is smaller than the sum of its proper divisors (29079519544).

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

21020187680 is a wasteful number, since it uses less digits than its factorization.

21020187680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1162749 (or 1162741 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 35.

Adding to 21020187680 its reverse (8678102012), we get a palindrome (29698289692).

The spelling of 21020187680 in words is "twenty-one billion, twenty million, one hundred eighty-seven thousand, six hundred eighty".