497821991 has 4 divisors (see below), whose sum is σ = 498225672. Its totient is φ = 497418312.

The previous prime is 497821981. The next prime is 497821997. The reversal of 497821991 is 199128794.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199128794 = 2 ⋅99564397.

It is a cyclic number.

It is not a de Polignac number, because 497821991 - 2⁶ = 497821927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (497821997) 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, 199985 + ... + 202458.

It is an arithmetic number, because the mean of its divisors is an integer number (124556418).

Almost surely, 2^497821991 is an apocalyptic number.

497821991 is a deficient number, since it is larger than the sum of its proper divisors (403681).

497821991 is a wasteful number, since it uses less digits than its factorization.

497821991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403680.

The product of its digits is 326592, while the sum is 50.

The square root of 497821991 is about 22311.9248609348. The cubic root of 497821991 is about 792.5463906210.

The spelling of 497821991 in words is "four hundred ninety-seven million, eight hundred twenty-one thousand, nine hundred ninety-one".