491997397 has 4 divisors (see below), whose sum is σ = 493118560. Its totient is φ = 490876236.

The previous prime is 491997353. The next prime is 491997409. The reversal of 491997397 is 793799194.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-491997397 is a prime.

It is a super-2 number, since 2×491997397² = 484122877309551218, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491997307) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 559923 + ... + 560800.

It is an arithmetic number, because the mean of its divisors is an integer number (123279640).

Almost surely, 2^491997397 is an apocalyptic number.

It is an amenable number.

491997397 is a deficient number, since it is larger than the sum of its proper divisors (1121163).

491997397 is a wasteful number, since it uses less digits than its factorization.

491997397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1121162.

The product of its digits is 3857868, while the sum is 58.

The square root of 491997397 is about 22181.0143365897. The cubic root of 491997397 is about 789.4432850691.

The spelling of 491997397 in words is "four hundred ninety-one million, nine hundred ninety-seven thousand, three hundred ninety-seven".