661769 has 2 divisors, whose sum is σ = 661770. Its totient is φ = 661768.

The previous prime is 661741. The next prime is 661777. The reversal of 661769 is 967166.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 511225 + 150544 = 715^2 + 388^2 .

It is a cyclic number.

It is not a de Polignac number, because 661769 - 2⁸ = 661513 is a prime.

It is a super-2 number, since 2×661769² = 875876418722, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (660769) 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, 330884 + 330885.

It is an arithmetic number, because the mean of its divisors is an integer number (330885).

2⁶⁶¹⁷⁶⁹ is an apocalyptic number.

It is an amenable number.

661769 is a deficient number, since it is larger than the sum of its proper divisors (1).

661769 is an equidigital number, since it uses as much as digits as its factorization.

661769 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13608, while the sum is 35.

The square root of 661769 is about 813.4918561362. The cubic root of 661769 is about 87.1435951615.

The spelling of 661769 in words is "six hundred sixty-one thousand, seven hundred sixty-nine".