221312031 has 4 divisors (see below), whose sum is σ = 295082712. Its totient is φ = 147541352.

The previous prime is 221312027. The next prime is 221312033. The reversal of 221312031 is 130213122.

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 221312031 - 2² = 221312027 is a prime.

It is a super-2 number, since 2×221312031² = 97958030130689922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221312031.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221312033) 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, 36885336 + ... + 36885341.

It is an arithmetic number, because the mean of its divisors is an integer number (73770678).

Almost surely, 2^221312031 is an apocalyptic number.

221312031 is a deficient number, since it is larger than the sum of its proper divisors (73770681).

221312031 is an equidigital number, since it uses as much as digits as its factorization.

221312031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73770680.

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 221312031 is about 14876.5597837672. The cubic root of 221312031 is about 604.8787690521.

Adding to 221312031 its reverse (130213122), we get a palindrome (351525153).

The spelling of 221312031 in words is "two hundred twenty-one million, three hundred twelve thousand, thirty-one".