221312021 has 16 divisors (see below), whose sum is σ = 262828800. Its totient is φ = 182329728.

The previous prime is 221312011. The next prime is 221312023. The reversal of 221312021 is 120213122.

It is a happy number.

It is not a de Polignac number, because 221312021 - 2¹⁴ = 221295637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221311987 and 221312005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221312023) 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, 44960 + ... + 49638.

It is an arithmetic number, because the mean of its divisors is an integer number (16426800).

Almost surely, 2^221312021 is an apocalyptic number.

It is an amenable number.

221312021 is a deficient number, since it is larger than the sum of its proper divisors (41516779).

221312021 is a wasteful number, since it uses less digits than its factorization.

221312021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4948.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 221312021 is about 14876.5594476680. The cubic root of 221312021 is about 604.8787599416.

Adding to 221312021 its reverse (120213122), we get a palindrome (341525143).

The spelling of 221312021 in words is "two hundred twenty-one million, three hundred twelve thousand, twenty-one".