21601898881920 has 1024 divisors, whose sum is σ = 90696864614400. Its totient is φ = 4756600848384.

The previous prime is 21601898881879. The next prime is 21601898881991. The reversal of 21601898881920 is 2918889810612.

21601898881920 is a `hidden beast` number, since 2 + 1 + 601 + 8 + 9 + 8 + 8 + 8 + 19 + 2 + 0 = 666.

It is a super-2 number, since 2×21601898881920² (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 127 ways as a sum of consecutive naturals, for example, 379664994 + ... + 379721886.

It is an arithmetic number, because the mean of its divisors is an integer number (88571156850).

Almost surely, 2^{21601898881920} is an apocalyptic number.

21601898881920 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 21601898881920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45348432307200).

21601898881920 is an abundant number, since it is smaller than the sum of its proper divisors (69094965732480).

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

21601898881920 is a wasteful number, since it uses less digits than its factorization.

21601898881920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57044 (or 57026 counting only the distinct ones).

The product of its (nonzero) digits is 7962624, while the sum is 63.

The spelling of 21601898881920 in words is "twenty-one trillion, six hundred one billion, eight hundred ninety-eight million, eight hundred eighty-one thousand, nine hundred twenty".