661873 has 2 divisors, whose sum is σ = 661874. Its totient is φ = 661872.

The previous prime is 661849. The next prime is 661877. The reversal of 661873 is 378166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 567009 + 94864 = 753^2 + 308^2 .

It is a cyclic number.

It is not a de Polignac number, because 661873 - 2⁹ = 661361 is a prime.

It is not a weakly prime, because it can be changed into another prime (661877) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330936 + 330937.

It is an arithmetic number, because the mean of its divisors is an integer number (330937).

2⁶⁶¹⁸⁷³ is an apocalyptic number.

It is an amenable number.

661873 is a deficient number, since it is larger than the sum of its proper divisors (1).

661873 is an equidigital number, since it uses as much as digits as its factorization.

661873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 31.

The square root of 661873 is about 813.5557755926. Note that the first 3 decimals coincide. The cubic root of 661873 is about 87.1481599261.

The spelling of 661873 in words is "six hundred sixty-one thousand, eight hundred seventy-three".