21391909418880 has 2048 divisors, whose sum is σ = 102719928729600. Its totient is φ = 4062968709120.

The previous prime is 21391909418849. The next prime is 21391909418897. The reversal of 21391909418880 is 8881490919312.

21391909418880 is a `hidden beast` number, since 2 + 1 + 391 + 9 + 0 + 94 + 1 + 88 + 80 = 666.

It is a super-2 number, since 2×21391909418880² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 1781613837 + ... + 1781625843.

It is an arithmetic number, because the mean of its divisors is an integer number (50156215200).

Almost surely, 2^{21391909418880} is an apocalyptic number.

21391909418880 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 21391909418880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (51359964364800).

21391909418880 is an abundant number, since it is smaller than the sum of its proper divisors (81328019310720).

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

21391909418880 is a wasteful number, since it uses less digits than its factorization.

21391909418880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12169 (or 12151 counting only the distinct ones).

The product of its (nonzero) digits is 8957952, while the sum is 63.

The spelling of 21391909418880 in words is "twenty-one trillion, three hundred ninety-one billion, nine hundred nine million, four hundred eighteen thousand, eight hundred eighty".