221220031 has 4 divisors (see below), whose sum is σ = 234232992. Its totient is φ = 208207072.

The previous prime is 221220007. The next prime is 221220037. The reversal of 221220031 is 130022122.

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

It is a cyclic number.

It is not a de Polignac number, because 221220031 - 2²⁷ = 87002303 is a prime.

It is a super-3 number, since 3×221220031³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221219993 and 221220020.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221220037) 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, 6506455 + ... + 6506488.

It is an arithmetic number, because the mean of its divisors is an integer number (58558248).

Almost surely, 2^221220031 is an apocalyptic number.

221220031 is a deficient number, since it is larger than the sum of its proper divisors (13012961).

221220031 is a wasteful number, since it uses less digits than its factorization.

221220031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13012960.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 221220031 is about 14873.4673496129. The cubic root of 221220031 is about 604.7949408640.

Adding to 221220031 its reverse (130022122), we get a palindrome (351242153).

The spelling of 221220031 in words is "two hundred twenty-one million, two hundred twenty thousand, thirty-one".