625661 has 2 divisors, whose sum is σ = 625662. Its totient is φ = 625660.

The previous prime is 625657. The next prime is 625663. The reversal of 625661 is 166526.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 592900 + 32761 = 770^2 + 181^2 .

It is a cyclic number.

It is not a de Polignac number, because 625661 - 2² = 625657 is a prime.

It is a Sophie Germain prime.

Together with 625663, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 625661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (625663) 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, 312830 + 312831.

It is an arithmetic number, because the mean of its divisors is an integer number (312831).

2⁶²⁵⁶⁶¹ is an apocalyptic number.

It is an amenable number.

625661 is a deficient number, since it is larger than the sum of its proper divisors (1).

625661 is an equidigital number, since it uses as much as digits as its factorization.

625661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 26.

The square root of 625661 is about 790.9873576739. The cubic root of 625661 is about 85.5289278903.

The spelling of 625661 in words is "six hundred twenty-five thousand, six hundred sixty-one".