21018400704 has 336 divisors, whose sum is σ = 76743763200. Its totient is φ = 5354201088.

The previous prime is 21018400639. The next prime is 21018400727. The reversal of 21018400704 is 40700481012.

It is a tau number, because it is divible by the number of its divisors (336).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1294267 + ... + 1310405.

Almost surely, 2^21018400704 is an apocalyptic number.

21018400704 is a gapful number since it is divisible by the number (24) 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 21018400704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38371881600).

21018400704 is an abundant number, since it is smaller than the sum of its proper divisors (55725362496).

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

21018400704 is a wasteful number, since it uses less digits than its factorization.

21018400704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16200 (or 16187 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

Adding to 21018400704 its reverse (40700481012), we get a palindrome (61718881716).

The spelling of 21018400704 in words is "twenty-one billion, eighteen million, four hundred thousand, seven hundred four".