30831221 has 6 divisors (see below), whose sum is σ = 31603266. Its totient is φ = 30077600.

The previous prime is 30831209. The next prime is 30831289. The reversal of 30831221 is 12213803.

It can be written as a sum of positive squares in 3 ways, for example, as 4708900 + 26122321 = 2170^2 + 5111^2 .

It is a de Polignac number, because none of the positive numbers 2^k-30831221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 30831193 and 30831202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30831121) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7490 + ... + 10851.

It is an arithmetic number, because the mean of its divisors is an integer number (5267211).

Almost surely, 2^30831221 is an apocalyptic number.

It is an amenable number.

30831221 is a deficient number, since it is larger than the sum of its proper divisors (772045).

30831221 is an equidigital number, since it uses as much as digits as its factorization.

30831221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18423 (or 18382 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 30831221 is about 5552.5868746018. The cubic root of 30831221 is about 313.5669209098.

The spelling of 30831221 in words is "thirty million, eight hundred thirty-one thousand, two hundred twenty-one".