997661957 has 2 divisors, whose sum is σ = 997661958. Its totient is φ = 997661956.

The previous prime is 997661953. The next prime is 997661989. The reversal of 997661957 is 759166799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 955489921 + 42172036 = 30911^2 + 6494^2 .

It is a cyclic number.

It is not a de Polignac number, because 997661957 - 2² = 997661953 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 997661896 and 997661905.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (997661953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498830978 + 498830979.

It is an arithmetic number, because the mean of its divisors is an integer number (498830979).

Almost surely, 2^997661957 is an apocalyptic number.

It is an amenable number.

997661957 is a deficient number, since it is larger than the sum of its proper divisors (1).

997661957 is an equidigital number, since it uses as much as digits as its factorization.

997661957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6429780, while the sum is 59.

The square root of 997661957 is about 31585.7872626281. The cubic root of 997661957 is about 999.2200441604.

The spelling of 997661957 in words is "nine hundred ninety-seven million, six hundred sixty-one thousand, nine hundred fifty-seven".