615661 has 2 divisors, whose sum is σ = 615662.
Its totient is φ = 615660.
The previous prime is 615623. The next prime is 615677. The reversal of 615661 is 166516.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 447561 + 168100 = 669^2 + 410^2
It is a cyclic number.
It is not a de Polignac number, because 615661 - 219 = 91373 is a prime.
615661 is a lucky number.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (615161) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 307830 + 307831.
It is an arithmetic number, because the mean of its divisors is an integer number (307831).
2615661 is an apocalyptic number.
It is an amenable number.
615661 is a deficient number, since it is larger than the sum of its proper divisors (1).
615661 is an equidigital number, since it uses as much as digits as its factorization.
615661 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 1080, while the sum is 25.
The square root of 615661 is about 784.6406820960.
The cubic root of 615661 is about 85.0708060532.
The spelling of 615661 in words is "six hundred fifteen thousand, six hundred sixty-one".