491680921 has 8 divisors (see below), whose sum is σ = 493858944. Its totient is φ = 489508560.

The previous prime is 491680883. The next prime is 491680939. The reversal of 491680921 is 129086194.

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 491680921 - 2⁷ = 491680793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (491680951) 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, 280570 + ... + 282316.

It is an arithmetic number, because the mean of its divisors is an integer number (61732368).

Almost surely, 2^491680921 is an apocalyptic number.

It is an amenable number.

491680921 is a deficient number, since it is larger than the sum of its proper divisors (2178023).

491680921 is a wasteful number, since it uses less digits than its factorization.

491680921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2831.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 491680921 is about 22173.8792501448. The cubic root of 491680921 is about 789.2739796735.

The spelling of 491680921 in words is "four hundred ninety-one million, six hundred eighty thousand, nine hundred twenty-one".