221031 has 12 divisors (see below), whose sum is σ = 327600. Its totient is φ = 143520.

The previous prime is 221021. The next prime is 221047. The reversal of 221031 is 130122.

It is a happy number.

It is not a de Polignac number, because 221031 - 2⁷ = 220903 is a prime.

It is a super-2 number, since 2×221031² = 97709405922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221021) 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 11 ways as a sum of consecutive naturals, for example, 70 + ... + 668.

It is an arithmetic number, because the mean of its divisors is an integer number (27300).

2²²¹⁰³¹ is an apocalyptic number.

221031 is a deficient number, since it is larger than the sum of its proper divisors (106569).

221031 is a wasteful number, since it uses less digits than its factorization.

221031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 646 (or 643 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 221031 is about 470.1393410469. The cubic root of 221031 is about 60.4622627397.

Adding to 221031 its reverse (130122), we get a palindrome (351153).

Subtracting from 221031 its reverse (130122), we obtain a palindrome (90909).

The spelling of 221031 in words is "two hundred twenty-one thousand, thirty-one".