221688936 has 144 divisors (see below), whose sum is σ = 721319040. Its totient is φ = 61266240.

The previous prime is 221688923. The next prime is 221688949. The reversal of 221688936 is 639886122.

221688936 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (221688923) and next prime (221688949).

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

It is a junction number, because it is equal to n+sod(n) for n = 221688891 and 221688900.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 108355 + ... + 110381.

It is an arithmetic number, because the mean of its divisors is an integer number (5009160).

Almost surely, 2^221688936 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 221688936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (360659520).

221688936 is an abundant number, since it is smaller than the sum of its proper divisors (499630104).

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

221688936 is a wasteful number, since it uses less digits than its factorization.

221688936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2084 (or 2070 counting only the distinct ones).

The product of its digits is 248832, while the sum is 45.

The square root of 221688936 is about 14889.2221422074. Note that the first 3 decimals coincide. The cubic root of 221688936 is about 605.2219534878.

The spelling of 221688936 in words is "two hundred twenty-one million, six hundred eighty-eight thousand, nine hundred thirty-six".