21581673937920 has 704 divisors, whose sum is σ = 81316272576000. Its totient is φ = 5412896243712.

The previous prime is 21581673937909. The next prime is 21581673937921. The reversal of 21581673937920 is 2973937618512.

21581673937920 is a `hidden beast` number, since 2 + 1 + 58 + 167 + 39 + 379 + 20 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21581673937921) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 365062284 + ... + 365121396.

It is an arithmetic number, because the mean of its divisors is an integer number (115506069000).

Almost surely, 2^{21581673937920} is an apocalyptic number.

21581673937920 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 21581673937920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40658136288000).

21581673937920 is an abundant number, since it is smaller than the sum of its proper divisors (59734598638080).

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

21581673937920 is a wasteful number, since it uses less digits than its factorization.

21581673937920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59305 (or 59281 counting only the distinct ones).

The product of its (nonzero) digits is 34292160, while the sum is 63.

The spelling of 21581673937920 in words is "twenty-one trillion, five hundred eighty-one billion, six hundred seventy-three million, nine hundred thirty-seven thousand, nine hundred twenty".