661997737 has 2 divisors, whose sum is σ = 661997738. Its totient is φ = 661997736.

The previous prime is 661997729. The next prime is 661997813. The reversal of 661997737 is 737799166.

It is a happy number.

661997737 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 594823321 + 67174416 = 24389^2 + 8196^2 .

It is a cyclic number.

It is not a de Polignac number, because 661997737 - 2³ = 661997729 is a prime.

It is not a weakly prime, because it can be changed into another prime (661997717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330998868 + 330998869.

It is an arithmetic number, because the mean of its divisors is an integer number (330998869).

Almost surely, 2^661997737 is an apocalyptic number.

It is an amenable number.

661997737 is a deficient number, since it is larger than the sum of its proper divisors (1).

661997737 is an equidigital number, since it uses as much as digits as its factorization.

661997737 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3000564, while the sum is 55.

The square root of 661997737 is about 25729.3166835033. The cubic root of 661997737 is about 871.5363424780.

The spelling of 661997737 in words is "six hundred sixty-one million, nine hundred ninety-seven thousand, seven hundred thirty-seven".