21878567640 has 256 divisors, whose sum is σ = 77853312000. Its totient is φ = 5449006080.

The previous prime is 21878567609. The next prime is 21878567663. The reversal of 21878567640 is 4676587812.

21878567640 is a `hidden beast` number, since 2 + 1 + 8 + 78 + 567 + 6 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

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, 1449412 + ... + 1464428.

It is an arithmetic number, because the mean of its divisors is an integer number (304114500).

Almost surely, 2^21878567640 is an apocalyptic number.

21878567640 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 21878567640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38926656000).

21878567640 is an abundant number, since it is smaller than the sum of its proper divisors (55974744360).

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

21878567640 is a wasteful number, since it uses less digits than its factorization.

21878567640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15127 (or 15117 counting only the distinct ones).

The product of its (nonzero) digits is 4515840, while the sum is 54.

The spelling of 21878567640 in words is "twenty-one billion, eight hundred seventy-eight million, five hundred sixty-seven thousand, six hundred forty".