690661 has 2 divisors, whose sum is σ = 690662. Its totient is φ = 690660.

The previous prime is 690629. The next prime is 690673. The reversal of 690661 is 166096.

It is a happy number.

690661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 690561 + 100 = 831^2 + 10^2 .

It is a cyclic number.

It is not a de Polignac number, because 690661 - 2⁵ = 690629 is a prime.

It is a Chen prime.

It is a nialpdrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (690611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345330 + 345331.

It is an arithmetic number, because the mean of its divisors is an integer number (345331).

2⁶⁹⁰⁶⁶¹ is an apocalyptic number.

It is an amenable number.

690661 is a deficient number, since it is larger than the sum of its proper divisors (1).

690661 is an equidigital number, since it uses as much as digits as its factorization.

690661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 690661 is about 831.0601662936. The cubic root of 690661 is about 88.3937674332.

The spelling of 690661 in words is "six hundred ninety thousand, six hundred sixty-one".