21856401600 has 336 divisors, whose sum is σ = 78692630016. Its totient is φ = 5266944000.

The previous prime is 21856401571. The next prime is 21856401617. The reversal of 21856401600 is 610465812.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9555657 + ... + 9557943.

It is an arithmetic number, because the mean of its divisors is an integer number (234204256).

Almost surely, 2^21856401600 is an apocalyptic number.

21856401600 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 21856401600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39346315008).

21856401600 is an abundant number, since it is smaller than the sum of its proper divisors (56836228416).

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

21856401600 is a wasteful number, since it uses less digits than its factorization.

21856401600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2504 (or 2489 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 33.

The spelling of 21856401600 in words is "twenty-one billion, eight hundred fifty-six million, four hundred one thousand, six hundred".