221390688 has 24 divisors (see below), whose sum is σ = 581150808. Its totient is φ = 73796864.

The previous prime is 221390671. The next prime is 221390707. The reversal of 221390688 is 886093122.

It is a happy number.

221390688 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×221390688² = 98027673466226688, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1152981 + ... + 1153172.

It is an arithmetic number, because the mean of its divisors is an integer number (24214617).

Almost surely, 2^221390688 is an apocalyptic number.

It is an amenable number.

221390688 is an abundant number, since it is smaller than the sum of its proper divisors (359760120).

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

221390688 is a wasteful number, since it uses less digits than its factorization.

221390688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2306166 (or 2306158 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 39.

The square root of 221390688 is about 14879.2032044730. The cubic root of 221390688 is about 604.9504209992.

The spelling of 221390688 in words is "two hundred twenty-one million, three hundred ninety thousand, six hundred eighty-eight".