661897 has 2 divisors, whose sum is σ = 661898. Its totient is φ = 661896.

The previous prime is 661889. The next prime is 661909. The reversal of 661897 is 798166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 395641 + 266256 = 629^2 + 516^2 .

It is a cyclic number.

It is not a de Polignac number, because 661897 - 2³ = 661889 is a prime.

It is not a weakly prime, because it can be changed into another prime (661877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330948 + 330949.

It is an arithmetic number, because the mean of its divisors is an integer number (330949).

2⁶⁶¹⁸⁹⁷ is an apocalyptic number.

It is an amenable number.

661897 is a deficient number, since it is larger than the sum of its proper divisors (1).

661897 is an equidigital number, since it uses as much as digits as its factorization.

661897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 37.

The square root of 661897 is about 813.5705255231. The cubic root of 661897 is about 87.1492132654.

The spelling of 661897 in words is "six hundred sixty-one thousand, eight hundred ninety-seven".