21528842400 has 432 divisors, whose sum is σ = 82299966840. Its totient is φ = 5295513600.

The previous prime is 21528842399. The next prime is 21528842407. The reversal of 21528842400 is 424882512.

21528842400 is a `hidden beast` number, since 2 + 152 + 88 + 424 + 0 + 0 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 13379086224 + 8149756176 = 115668^2 + 90276^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21528842407) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 15817720 + ... + 15819080.

Almost surely, 2^21528842400 is an apocalyptic number.

21528842400 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 21528842400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41149983420).

21528842400 is an abundant number, since it is smaller than the sum of its proper divisors (60771124440).

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

21528842400 is a wasteful number, since it uses less digits than its factorization.

21528842400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1426 (or 1384 counting only the distinct ones).

The product of its (nonzero) digits is 40960, while the sum is 36.

The spelling of 21528842400 in words is "twenty-one billion, five hundred twenty-eight million, eight hundred forty-two thousand, four hundred".