221221001 has 4 divisors (see below), whose sum is σ = 221291904. Its totient is φ = 221150100.

The previous prime is 221220997. The next prime is 221221037. The reversal of 221221001 is 100122122.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 100122122 = 2 ⋅50061061.

It is a cyclic number.

It is not a de Polignac number, because 221221001 - 2² = 221220997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221221081) 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 3 ways as a sum of consecutive naturals, for example, 30545 + ... + 37086.

It is an arithmetic number, because the mean of its divisors is an integer number (55322976).

Almost surely, 2^221221001 is an apocalyptic number.

It is an amenable number.

221221001 is a deficient number, since it is larger than the sum of its proper divisors (70903).

221221001 is an equidigital number, since it uses as much as digits as its factorization.

221221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70902.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 221221001 is about 14873.4999579790. The cubic root of 221221001 is about 604.7958248259.

Adding to 221221001 its reverse (100122122), we get a palindrome (321343123).

It can be divided in two parts, 22122 and 1001, that multiplied together give a palindrome (22144122).

The spelling of 221221001 in words is "two hundred twenty-one million, two hundred twenty-one thousand, one".