221660816 has 20 divisors (see below), whose sum is σ = 462504252. Its totient is φ = 102304896.

The previous prime is 221660797. The next prime is 221660837. The reversal of 221660816 is 618066122.

It can be written as a sum of positive squares in 2 ways, for example, as 57820816 + 163840000 = 7604^2 + 12800^2 .

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, 532631 + ... + 533046.

Almost surely, 2^221660816 is an apocalyptic number.

221660816 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

221660816 is an abundant number, since it is smaller than the sum of its proper divisors (240843436).

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

221660816 is a wasteful number, since it uses less digits than its factorization.

221660816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1065698 (or 1065692 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 221660816 is about 14888.2778050384. The cubic root of 221660816 is about 605.1963627339.

The spelling of 221660816 in words is "two hundred twenty-one million, six hundred sixty thousand, eight hundred sixteen".