221397904 has 80 divisors (see below), whose sum is σ = 535437952. Its totient is φ = 86344704.

The previous prime is 221397893. The next prime is 221397923. The reversal of 221397904 is 409793122.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 105247 + ... + 107329.

Almost surely, 2^221397904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221397904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (267718976).

221397904 is an abundant number, since it is smaller than the sum of its proper divisors (314040048).

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

221397904 is a wasteful number, since it uses less digits than its factorization.

221397904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2184 (or 2178 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 221397904 is about 14879.4456886001. The cubic root of 221397904 is about 604.9569935051.

The spelling of 221397904 in words is "two hundred twenty-one million, three hundred ninety-seven thousand, nine hundred four".