221020818 has 8 divisors (see below), whose sum is σ = 442041648. Its totient is φ = 73673604.

The previous prime is 221020781. The next prime is 221020819. The reversal of 221020818 is 818020122.

It is a sphenic number, since it is the product of 3 distinct primes.

221020818 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (221020819) 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 3 ways as a sum of consecutive naturals, for example, 18418396 + ... + 18418407.

It is an arithmetic number, because the mean of its divisors is an integer number (55255206).

Almost surely, 2^221020818 is an apocalyptic number.

221020818 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

221020818 is a wasteful number, since it uses less digits than its factorization.

221020818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36836808.

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 221020818 is about 14866.7689159414. The cubic root of 221020818 is about 604.6133430857.

The spelling of 221020818 in words is "two hundred twenty-one million, twenty thousand, eight hundred eighteen".