31553021 has 2 divisors, whose sum is σ = 31553022. Its totient is φ = 31553020.

The previous prime is 31553017. The next prime is 31553063. The reversal of 31553021 is 12035513.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29008996 + 2544025 = 5386^2 + 1595^2 .

It is a cyclic number.

It is not a de Polignac number, because 31553021 - 2² = 31553017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31552984 and 31553002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31553321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15776510 + 15776511.

It is an arithmetic number, because the mean of its divisors is an integer number (15776511).

Almost surely, 2^31553021 is an apocalyptic number.

It is an amenable number.

31553021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31553021 is an equidigital number, since it uses as much as digits as its factorization.

31553021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 450, while the sum is 20.

The square root of 31553021 is about 5617.2075802840. The cubic root of 31553021 is about 315.9950761664.

Adding to 31553021 its reverse (12035513), we get a palindrome (43588534).

The spelling of 31553021 in words is "thirty-one million, five hundred fifty-three thousand, twenty-one".