21166600400 has 240 divisors, whose sum is σ = 59649039360. Its totient is φ = 7135372800.

The previous prime is 21166600393. The next prime is 21166600409. The reversal of 21166600400 is 400666112.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21166600400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21166600409) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3926507 + ... + 3931893.

It is an arithmetic number, because the mean of its divisors is an integer number (248537664).

Almost surely, 2^21166600400 is an apocalyptic number.

21166600400 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 21166600400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29824519680).

21166600400 is an abundant number, since it is smaller than the sum of its proper divisors (38482438960).

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

21166600400 is a wasteful number, since it uses less digits than its factorization.

21166600400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5482 (or 5471 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 26.

The spelling of 21166600400 in words is "twenty-one billion, one hundred sixty-six million, six hundred thousand, four hundred".