661121 has 2 divisors, whose sum is σ = 661122. Its totient is φ = 661120.

The previous prime is 661117. The next prime is 661139. The reversal of 661121 is 121166.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 577600 + 83521 = 760^2 + 289^2 .

It is a cyclic number.

It is not a de Polignac number, because 661121 - 2² = 661117 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661121.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661121.

It is not a weakly prime, because it can be changed into another prime (661321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330560 + 330561.

It is an arithmetic number, because the mean of its divisors is an integer number (330561).

2⁶⁶¹¹²¹ is an apocalyptic number.

It is an amenable number.

661121 is a deficient number, since it is larger than the sum of its proper divisors (1).

661121 is an equidigital number, since it uses as much as digits as its factorization.

661121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72, while the sum is 17.

The square root of 661121 is about 813.0934755611. The cubic root of 661121 is about 87.1151423876.

Adding to 661121 its reverse (121166), we get a palindrome (782287).

It can be divided in two parts, 6611 and 21, that multiplied together give a palindrome (138831).

The spelling of 661121 in words is "six hundred sixty-one thousand, one hundred twenty-one".