661439 has 2 divisors, whose sum is σ = 661440. Its totient is φ = 661438.

The previous prime is 661421. The next prime is 661459. The reversal of 661439 is 934166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661439 - 2⁸ = 661183 is a prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661459) 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, 330719 + 330720.

It is an arithmetic number, because the mean of its divisors is an integer number (330720).

2⁶⁶¹⁴³⁹ is an apocalyptic number.

661439 is a deficient number, since it is larger than the sum of its proper divisors (1).

661439 is an equidigital number, since it uses as much as digits as its factorization.

661439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 29.

The square root of 661439 is about 813.2890015241. The cubic root of 661439 is about 87.1291076450.

The spelling of 661439 in words is "six hundred sixty-one thousand, four hundred thirty-nine".