491871666 has 32 divisors (see below), whose sum is σ = 1155728448. Its totient is φ = 137586240.

The previous prime is 491871647. The next prime is 491871701. The reversal of 491871666 is 666178194.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 285781 + ... + 287496.

It is an arithmetic number, because the mean of its divisors is an integer number (36116514).

Almost surely, 2^491871666 is an apocalyptic number.

491871666 is an abundant number, since it is smaller than the sum of its proper divisors (663856782).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

491871666 is a wasteful number, since it uses less digits than its factorization.

491871666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 573306.

The product of its digits is 435456, while the sum is 48.

The square root of 491871666 is about 22178.1799523766. The cubic root of 491871666 is about 789.3760313596.

The spelling of 491871666 in words is "four hundred ninety-one million, eight hundred seventy-one thousand, six hundred sixty-six".