491407978 has 4 divisors (see below), whose sum is σ = 737111970. Its totient is φ = 245703988.

The previous prime is 491407957. The next prime is 491407979. The reversal of 491407978 is 879704194.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 383102329 + 108305649 = 19573^2 + 10407^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (491407979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 122851993 + ... + 122851996.

Almost surely, 2^491407978 is an apocalyptic number.

491407978 is a deficient number, since it is larger than the sum of its proper divisors (245703992).

491407978 is a wasteful number, since it uses less digits than its factorization.

491407978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245703991.

The product of its (nonzero) digits is 508032, while the sum is 49.

The square root of 491407978 is about 22167.7237893294. The cubic root of 491407978 is about 789.1279048014.

The spelling of 491407978 in words is "four hundred ninety-one million, four hundred seven thousand, nine hundred seventy-eight".