221661560 has 32 divisors (see below), whose sum is σ = 510341040. Its totient is φ = 86601984.

The previous prime is 221661551. The next prime is 221661571. The reversal of 221661560 is 65166122.

221661560 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 62717 + ... + 66156.

Almost surely, 2^221661560 is an apocalyptic number.

221661560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221661560 is an abundant number, since it is smaller than the sum of its proper divisors (288679480).

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

221661560 is a wasteful number, since it uses less digits than its factorization.

221661560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128927 (or 128923 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 221661560 is about 14888.3027911176. The cubic root of 221661560 is about 605.1970398429.

The spelling of 221661560 in words is "two hundred twenty-one million, six hundred sixty-one thousand, five hundred sixty".