221138688 has 72 divisors (see below), whose sum is σ = 608907600. Its totient is φ = 71163904.

The previous prime is 221138651. The next prime is 221138693. The reversal of 221138688 is 886831122.

It is a super-2 number, since 2×221138688² = 97804638660722688, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17308 + ... + 27236.

It is an arithmetic number, because the mean of its divisors is an integer number (8457050).

Almost surely, 2^221138688 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 221138688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (304453800).

221138688 is an abundant number, since it is smaller than the sum of its proper divisors (387768912).

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

221138688 is an equidigital number, since it uses as much as digits as its factorization.

221138688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9977 (or 9963 counting only the distinct ones).

The product of its digits is 36864, while the sum is 39.

The square root of 221138688 is about 14870.7325979590. The cubic root of 221138688 is about 604.7208037169.

The spelling of 221138688 in words is "two hundred twenty-one million, one hundred thirty-eight thousand, six hundred eighty-eight".