21008839680 has 132 divisors (see below), whose sum is σ = 72795242052. Its totient is φ = 5602344960.

The previous prime is 21008839673. The next prime is 21008839693. The reversal of 21008839680 is 8693880012.

21008839680 is a `hidden beast` number, since 2 + 100 + 88 + 396 + 80 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 12103520256 + 8905319424 = 110016^2 + 94368^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 181881 + ... + 274040.

Almost surely, 2^21008839680 is an apocalyptic number.

21008839680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21008839680 is an abundant number, since it is smaller than the sum of its proper divisors (51786402372).

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

21008839680 is a wasteful number, since it uses less digits than its factorization.

21008839680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 455952 (or 455931 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The spelling of 21008839680 in words is "twenty-one billion, eight million, eight hundred thirty-nine thousand, six hundred eighty".