21001313642400 has 3456 divisors, whose sum is σ = 100182487910400. Its totient is φ = 4202672947200.

The previous prime is 21001313642399. The next prime is 21001313642471. The reversal of 21001313642400 is 424631310012.

It is a happy number.

21001313642400 is a `hidden beast` number, since 2 + 1 + 0 + 0 + 1 + 3 + 13 + 642 + 4 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 575 ways as a sum of consecutive naturals, for example, 22606365136 + ... + 22606366064.

It is an arithmetic number, because the mean of its divisors is an integer number (28987988400).

Almost surely, 2^{21001313642400} is an apocalyptic number.

21001313642400 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 21001313642400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50091243955200).

21001313642400 is an abundant number, since it is smaller than the sum of its proper divisors (79181174268000).

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

21001313642400 is a wasteful number, since it uses less digits than its factorization.

21001313642400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1069 (or 1043 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

Adding to 21001313642400 its reverse (424631310012), we get a palindrome (21425944952412).

The spelling of 21001313642400 in words is "twenty-one trillion, one billion, three hundred thirteen million, six hundred forty-two thousand, four hundred".