221540643 has 16 divisors (see below), whose sum is σ = 328732800. Its totient is φ = 147457800.

The previous prime is 221540633. The next prime is 221540677. The reversal of 221540643 is 346045122.

221540643 is a `hidden beast` number, since 2 + 2 + 15 + 4 + 0 + 643 = 666.

It is not a de Polignac number, because 221540643 - 2⁸ = 221540387 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (221540633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11568 + ... + 24018.

It is an arithmetic number, because the mean of its divisors is an integer number (20545800).

Almost surely, 2^221540643 is an apocalyptic number.

221540643 is a deficient number, since it is larger than the sum of its proper divisors (107192157).

221540643 is a wasteful number, since it uses less digits than its factorization.

221540643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13119 (or 13113 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 221540643 is about 14884.2414317962. The cubic root of 221540643 is about 605.0869742684.

Adding to 221540643 its reverse (346045122), we get a palindrome (567585765).

The spelling of 221540643 in words is "two hundred twenty-one million, five hundred forty thousand, six hundred forty-three".