21409639680 has 576 divisors, whose sum is σ = 81227317248. Its totient is φ = 4737761280.

The previous prime is 21409639651. The next prime is 21409639753. The reversal of 21409639680 is 8693690412.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 69738087 + ... + 69738393.

It is an arithmetic number, because the mean of its divisors is an integer number (141019648).

Almost surely, 2^21409639680 is an apocalyptic number.

21409639680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21409639680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40613658624).

21409639680 is an abundant number, since it is smaller than the sum of its proper divisors (59817677568).

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

21409639680 is a wasteful number, since it uses less digits than its factorization.

21409639680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482 (or 468 counting only the distinct ones).

The product of its (nonzero) digits is 559872, while the sum is 48.

The spelling of 21409639680 in words is "twenty-one billion, four hundred nine million, six hundred thirty-nine thousand, six hundred eighty".