31020221 has 2 divisors, whose sum is σ = 31020222. Its totient is φ = 31020220.

The previous prime is 31020191. The next prime is 31020233. The reversal of 31020221 is 12202013.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25908100 + 5112121 = 5090^2 + 2261^2 .

It is a cyclic number.

It is not a de Polignac number, because 31020221 - 2¹⁴ = 31003837 is a prime.

It is a super-2 number, since 2×31020221² = 1924508221777682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31020251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15510110 + 15510111.

It is an arithmetic number, because the mean of its divisors is an integer number (15510111).

Almost surely, 2^31020221 is an apocalyptic number.

It is an amenable number.

31020221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31020221 is an equidigital number, since it uses as much as digits as its factorization.

31020221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 31020221 is about 5569.5799662093. The cubic root of 31020221 is about 314.2063534667.

Adding to 31020221 its reverse (12202013), we get a palindrome (43222234).

The spelling of 31020221 in words is "thirty-one million, twenty thousand, two hundred twenty-one".