221245400 has 48 divisors (see below), whose sum is σ = 516194640. Its totient is φ = 88188800.

The previous prime is 221245397. The next prime is 221245421. The reversal of 221245400 is 4542122.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 60422 + ... + 63978.

It is an arithmetic number, because the mean of its divisors is an integer number (10754055).

Almost surely, 2^221245400 is an apocalyptic number.

221245400 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 221245400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (258097320).

221245400 is an abundant number, since it is smaller than the sum of its proper divisors (294949240).

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

221245400 is a wasteful number, since it uses less digits than its factorization.

221245400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3884 (or 3875 counting only the distinct ones).

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

The square root of 221245400 is about 14874.3201525313. The cubic root of 221245400 is about 604.8180588073.

Adding to 221245400 its reverse (4542122), we get a palindrome (225787522).

The spelling of 221245400 in words is "two hundred twenty-one million, two hundred forty-five thousand, four hundred".