21220304400 has 480 divisors, whose sum is σ = 81951004800. Its totient is φ = 5194137600.

The previous prime is 21220304389. The next prime is 21220304437. The reversal of 21220304400 is 440302212.

21220304400 is a `hidden beast` number, since 2 + 1 + 220 + 3 + 0 + 440 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 7526191 + ... + 7529009.

It is an arithmetic number, because the mean of its divisors is an integer number (170731260).

Almost surely, 2^21220304400 is an apocalyptic number.

21220304400 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 21220304400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40975502400).

21220304400 is an abundant number, since it is smaller than the sum of its proper divisors (60730700400).

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

21220304400 is a wasteful number, since it uses less digits than its factorization.

21220304400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2904 (or 2887 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

Adding to 21220304400 its reverse (440302212), we get a palindrome (21660606612).

The spelling of 21220304400 in words is "twenty-one billion, two hundred twenty million, three hundred four thousand, four hundred".