1997287491 has 12 divisors (see below), whose sum is σ = 2736975192. Its totient is φ = 1295535168.

The previous prime is 1997287477. The next prime is 1997287511. The reversal of 1997287491 is 1947827991.

It is not a de Polignac number, because 1997287491 - 2⁵ = 1997287459 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1997287441) 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 11 ways as a sum of consecutive naturals, for example, 239050 + ... + 247263.

It is an arithmetic number, because the mean of its divisors is an integer number (228081266).

Almost surely, 2^1997287491 is an apocalyptic number.

1997287491 is a deficient number, since it is larger than the sum of its proper divisors (739687701).

1997287491 is an equidigital number, since it uses as much as digits as its factorization.

1997287491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 486390 (or 486353 counting only the distinct ones).

The product of its digits is 2286144, while the sum is 57.

The square root of 1997287491 is about 44691.0224877436. The cubic root of 1997287491 is about 1259.3512009993.

The spelling of 1997287491 in words is "one billion, nine hundred ninety-seven million, two hundred eighty-seven thousand, four hundred ninety-one".