221444021 has 4 divisors (see below), whose sum is σ = 221681292. Its totient is φ = 221206752.

The previous prime is 221444009. The next prime is 221444033. The reversal of 221444021 is 120444122.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (221444009) and next prime (221444033).

It can be written as a sum of positive squares in 2 ways, for example, as 62331025 + 159112996 = 7895^2 + 12614^2 .

It is a cyclic number.

It is not a de Polignac number, because 221444021 - 2¹⁰ = 221442997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221443984 and 221444002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221444071) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117230 + ... + 119103.

It is an arithmetic number, because the mean of its divisors is an integer number (55420323).

Almost surely, 2^221444021 is an apocalyptic number.

It is an amenable number.

221444021 is a deficient number, since it is larger than the sum of its proper divisors (237271).

221444021 is an equidigital number, since it uses as much as digits as its factorization.

221444021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 237270.

The product of its (nonzero) digits is 512, while the sum is 20.

The square root of 221444021 is about 14880.9952960143. The cubic root of 221444021 is about 604.9989946025.

Adding to 221444021 its reverse (120444122), we get a palindrome (341888143).

The spelling of 221444021 in words is "two hundred twenty-one million, four hundred forty-four thousand, twenty-one".