221556645 has 12 divisors (see below), whose sum is σ = 384031596. Its totient is φ = 118163520.

The previous prime is 221556619. The next prime is 221556653. The reversal of 221556645 is 546655122.

221556645 is a `hidden beast` number, since 2 + 2 + 1 + 5 + 5 + 6 + 645 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 49999041 + 171557604 = 7071^2 + 13098^2 .

It is not a de Polignac number, because 221556645 - 2⁵ = 221556613 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2461696 + ... + 2461785.

It is an arithmetic number, because the mean of its divisors is an integer number (32002633).

Almost surely, 2^221556645 is an apocalyptic number.

It is an amenable number.

221556645 is a deficient number, since it is larger than the sum of its proper divisors (162474951).

221556645 is a wasteful number, since it uses less digits than its factorization.

221556645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4923492 (or 4923489 counting only the distinct ones).

The product of its digits is 72000, while the sum is 36.

The square root of 221556645 is about 14884.7789704785. The cubic root of 221556645 is about 605.1015425037.

The spelling of 221556645 in words is "two hundred twenty-one million, five hundred fifty-six thousand, six hundred forty-five".