997637989 has 2 divisors, whose sum is σ = 997637990. Its totient is φ = 997637988.

The previous prime is 997637957. The next prime is 997638007. The reversal of 997637989 is 989736799.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 997485889 + 152100 = 31583^2 + 390^2 .

It is an emirp because it is prime and its reverse (989736799) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 997637989 - 2⁵ = 997637957 is a prime.

It is a super-3 number, since 3×997637989³ (a number of 28 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (997637909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498818994 + 498818995.

It is an arithmetic number, because the mean of its divisors is an integer number (498818995).

Almost surely, 2^997637989 is an apocalyptic number.

It is an amenable number.

997637989 is a deficient number, since it is larger than the sum of its proper divisors (1).

997637989 is an equidigital number, since it uses as much as digits as its factorization.

997637989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46294416, while the sum is 67.

The square root of 997637989 is about 31585.4078491952. The cubic root of 997637989 is about 999.2120422857.

The spelling of 997637989 in words is "nine hundred ninety-seven million, six hundred thirty-seven thousand, nine hundred eighty-nine".