491981 has 8 divisors (see below), whose sum is σ = 571200. Its totient is φ = 415008.

The previous prime is 491977. The next prime is 491983. The reversal of 491981 is 189194.

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 491981 - 2² = 491977 is a prime.

It is a super-2 number, since 2×491981² = 484090608722, which contains 22 as substring.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 491981.

It is not an unprimeable number, because it can be changed into a prime (491983) 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, 56 + ... + 993.

It is an arithmetic number, because the mean of its divisors is an integer number (71400).

2⁴⁹¹⁹⁸¹ is an apocalyptic number.

It is an amenable number.

491981 is a deficient number, since it is larger than the sum of its proper divisors (79219).

491981 is a wasteful number, since it uses less digits than its factorization.

491981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1123.

The product of its digits is 2592, while the sum is 32.

The square root of 491981 is about 701.4135727230. The cubic root of 491981 is about 78.9434514938.

It can be divided in two parts, 491 and 981, that multiplied together give a triangular number (481671 = T₉₈₁).

The spelling of 491981 in words is "four hundred ninety-one thousand, nine hundred eighty-one".