221605256678400 has 1584 divisors, whose sum is σ = 941932152761600. Its totient is φ = 50569430630400.

The previous prime is 221605256678353. The next prime is 221605256678461. The reversal of 221605256678400 is 4876652506122.

221605256678400 is a `hidden beast` number, since 2 + 2 + 1 + 6 + 0 + 5 + 2 + 566 + 78 + 4 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 28783637751 + ... + 28783645449.

Almost surely, 2^{221605256678400} is an apocalyptic number.

221605256678400 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 221605256678400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (470966076380800).

221605256678400 is an abundant number, since it is smaller than the sum of its proper divisors (720326896083200).

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

221605256678400 is an equidigital number, since it uses as much as digits as its factorization.

221605256678400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8412 (or 8377 counting only the distinct ones).

The product of its (nonzero) digits is 9676800, while the sum is 54.

The spelling of 221605256678400 in words is "two hundred twenty-one trillion, six hundred five billion, two hundred fifty-six million, six hundred seventy-eight thousand, four hundred".