21881456640 has 960 divisors, whose sum is σ = 86763156480. Its totient is φ = 5255331840.

The previous prime is 21881456587. The next prime is 21881456651. The reversal of 21881456640 is 4665418812.

It is a happy number.

21881456640 is a `hidden beast` number, since 2 + 1 + 8 + 81 + 4 + 566 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (960).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 591390702 + ... + 591390738.

It is an arithmetic number, because the mean of its divisors is an integer number (90378288).

Almost surely, 2^21881456640 is an apocalyptic number.

21881456640 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 21881456640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43381578240).

21881456640 is an abundant number, since it is smaller than the sum of its proper divisors (64881699840).

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

21881456640 is a wasteful number, since it uses less digits than its factorization.

21881456640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130 (or 101 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 45.

The spelling of 21881456640 in words is "twenty-one billion, eight hundred eighty-one million, four hundred fifty-six thousand, six hundred forty".