997991266 has 4 divisors (see below), whose sum is σ = 1496986902. Its totient is φ = 498995632.

The previous prime is 997991263. The next prime is 997991287. The reversal of 997991266 is 662199799.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 837234225 + 160757041 = 28935^2 + 12679^2 .

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 997991266.

It is not an unprimeable number, because it can be changed into a prime (997991263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 249497815 + ... + 249497818.

Almost surely, 2^997991266 is an apocalyptic number.

997991266 is a deficient number, since it is larger than the sum of its proper divisors (498995636).

997991266 is a wasteful number, since it uses less digits than its factorization.

997991266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 498995635.

The product of its digits is 3306744, while the sum is 58.

The square root of 997991266 is about 31590.9997625906. Note that the first 3 decimals coincide. The cubic root of 997991266 is about 999.3299731643.

The spelling of 997991266 in words is "nine hundred ninety-seven million, nine hundred ninety-one thousand, two hundred sixty-six".