221418561 has 48 divisors (see below), whose sum is σ = 369982080. Its totient is φ = 115315200.

The previous prime is 221418529. The next prime is 221418581. The reversal of 221418561 is 165814122.

It is not a de Polignac number, because 221418561 - 2⁵ = 221418529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221418511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 315511 + ... + 316211.

It is an arithmetic number, because the mean of its divisors is an integer number (7707960).

Almost surely, 2^221418561 is an apocalyptic number.

221418561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

221418561 is a deficient number, since it is larger than the sum of its proper divisors (148563519).

221418561 is a wasteful number, since it uses less digits than its factorization.

221418561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 826 (or 813 counting only the distinct ones).

The product of its digits is 3840, while the sum is 30.

The square root of 221418561 is about 14880.1398178915. The cubic root of 221418561 is about 604.9758076067.

The spelling of 221418561 in words is "two hundred twenty-one million, four hundred eighteen thousand, five hundred sixty-one".