21781057881024 has 252 divisors, whose sum is σ = 67757434258800. Its totient is φ = 6686584639488.

The previous prime is 21781057881019. The next prime is 21781057881029. The reversal of 21781057881024 is 42018875018712.

21781057881024 is a `hidden beast` number, since 21 + 7 + 8 + 10 + 578 + 8 + 10 + 24 = 666.

It is an interprime number because it is at equal distance from previous prime (21781057881019) and next prime (21781057881029).

It is a super-3 number, since 3×21781057881024³ (a number of 41 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21781057881029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 42479172 + ... + 42988860.

Almost surely, 2^{21781057881024} is an apocalyptic number.

21781057881024 is a gapful number since it is divisible by the number (24) 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 21781057881024, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33878717129400).

21781057881024 is an abundant number, since it is smaller than the sum of its proper divisors (45976376377776).

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

21781057881024 is a wasteful number, since it uses less digits than its factorization.

21781057881024 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510172 (or 510146 counting only the distinct ones).

The product of its (nonzero) digits is 2007040, while the sum is 54.

The spelling of 21781057881024 in words is "twenty-one trillion, seven hundred eighty-one billion, fifty-seven million, eight hundred eighty-one thousand, twenty-four".