997628321 has 2 divisors, whose sum is σ = 997628322. Its totient is φ = 997628320.

The previous prime is 997628309. The next prime is 997628327. The reversal of 997628321 is 123826799.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 817102225 + 180526096 = 28585^2 + 13436^2 .

It is a cyclic number.

It is not a de Polignac number, because 997628321 - 2⁶ = 997628257 is a prime.

It is a super-2 number, since 2×997628321² = 1990524533722558082, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (997628327) 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, 498814160 + 498814161.

It is an arithmetic number, because the mean of its divisors is an integer number (498814161).

Almost surely, 2^997628321 is an apocalyptic number.

It is an amenable number.

997628321 is a deficient number, since it is larger than the sum of its proper divisors (1).

997628321 is an equidigital number, since it uses as much as digits as its factorization.

997628321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 47.

The square root of 997628321 is about 31585.2548034680. The cubic root of 997628321 is about 999.2088145240.

The spelling of 997628321 in words is "nine hundred ninety-seven million, six hundred twenty-eight thousand, three hundred twenty-one".