31090561 has 2 divisors, whose sum is σ = 31090562. Its totient is φ = 31090560.

The previous prime is 31090559. The next prime is 31090571. The reversal of 31090561 is 16509013.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27499536 + 3591025 = 5244^2 + 1895^2 .

It is a cyclic number.

It is not a de Polignac number, because 31090561 - 2¹ = 31090559 is a prime.

Together with 31090559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (31090531) 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 as a sum of consecutive naturals, namely, 15545280 + 15545281.

It is an arithmetic number, because the mean of its divisors is an integer number (15545281).

Almost surely, 2^31090561 is an apocalyptic number.

It is an amenable number.

31090561 is a deficient number, since it is larger than the sum of its proper divisors (1).

31090561 is an equidigital number, since it uses as much as digits as its factorization.

31090561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 810, while the sum is 25.

The square root of 31090561 is about 5575.8910498682. The cubic root of 31090561 is about 314.4436673857.

Adding to 31090561 its reverse (16509013), we get a palindrome (47599574).

The spelling of 31090561 in words is "thirty-one million, ninety thousand, five hundred sixty-one".