997209091 has 16 divisors (see below), whose sum is σ = 1113926400. Its totient is φ = 888310368.

The previous prime is 997209071. The next prime is 997209131. The reversal of 997209091 is 190902799.

It is a cyclic number.

It is not a de Polignac number, because 997209091 - 2⁷ = 997208963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (997209071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6445 + ... + 45121.

It is an arithmetic number, because the mean of its divisors is an integer number (69620400).

Almost surely, 2^997209091 is an apocalyptic number.

997209091 is a deficient number, since it is larger than the sum of its proper divisors (116717309).

997209091 is a wasteful number, since it uses less digits than its factorization.

997209091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38778.

The product of its (nonzero) digits is 91854, while the sum is 46.

The square root of 997209091 is about 31578.6176233223. The cubic root of 997209091 is about 999.0688301919.

It can be divided in two parts, 99720 and 9091, that added together give a triangular number (108811 = T₄₆₆).

The spelling of 997209091 in words is "nine hundred ninety-seven million, two hundred nine thousand, ninety-one".