21005040404000 has 384 divisors, whose sum is σ = 55117493855424. Its totient is φ = 7839744000000.

The previous prime is 21005040403987. The next prime is 21005040404057. The reversal of 21005040404000 is 40404050012.

It can be written as a sum of positive squares in 32 ways, for example, as 529524003856 + 20475516400144 = 727684^2 + 4524988^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3818401250 + ... + 3818406750.

Almost surely, 2^{21005040404000} is an apocalyptic number.

21005040404000 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 21005040404000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27558746927712).

21005040404000 is an abundant number, since it is smaller than the sum of its proper divisors (34112453451424).

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

21005040404000 is a wasteful number, since it uses less digits than its factorization.

21005040404000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6017 (or 5999 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

Adding to 21005040404000 its reverse (40404050012), we get a palindrome (21045444454012).

The spelling of 21005040404000 in words is "twenty-one trillion, five billion, forty million, four hundred four thousand".