220531561 has 2 divisors, whose sum is σ = 220531562. Its totient is φ = 220531560.

The previous prime is 220531559. The next prime is 220531583. The reversal of 220531561 is 165135022.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 189227536 + 31304025 = 13756^2 + 5595^2 .

It is a cyclic number.

It is not a de Polignac number, because 220531561 - 2¹ = 220531559 is a prime.

Together with 220531559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (220535561) 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, 110265780 + 110265781.

It is an arithmetic number, because the mean of its divisors is an integer number (110265781).

Almost surely, 2^220531561 is an apocalyptic number.

It is an amenable number.

220531561 is a deficient number, since it is larger than the sum of its proper divisors (1).

220531561 is an equidigital number, since it uses as much as digits as its factorization.

220531561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 220531561 is about 14850.3050810413. The cubic root of 220531561 is about 604.1668846124.

Adding to 220531561 its reverse (165135022), we get a palindrome (385666583).

The spelling of 220531561 in words is "two hundred twenty million, five hundred thirty-one thousand, five hundred sixty-one".