491561993 has 8 divisors (see below), whose sum is σ = 532148736. Its totient is φ = 451371600.

The previous prime is 491561971. The next prime is 491562023. The reversal of 491561993 is 399165194.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 491561993 - 2¹⁰ = 491560969 is a prime.

It is a super-3 number, since 3×491561993³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (491561933) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96503 + ... + 101468.

It is an arithmetic number, because the mean of its divisors is an integer number (66518592).

Almost surely, 2^491561993 is an apocalyptic number.

It is an amenable number.

491561993 is a deficient number, since it is larger than the sum of its proper divisors (40586743).

491561993 is a wasteful number, since it uses less digits than its factorization.

491561993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198175.

The product of its digits is 262440, while the sum is 47.

The square root of 491561993 is about 22171.1973740707. The cubic root of 491561993 is about 789.2103378948.

The spelling of 491561993 in words is "four hundred ninety-one million, five hundred sixty-one thousand, nine hundred ninety-three".