491638729 has 2 divisors, whose sum is σ = 491638730. Its totient is φ = 491638728.

The previous prime is 491638727. The next prime is 491638733. The reversal of 491638729 is 927836194.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 276224400 + 215414329 = 16620^2 + 14677^2 .

It is a cyclic number.

It is not a de Polignac number, because 491638729 - 2¹ = 491638727 is a prime.

Together with 491638727, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (491638727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245819364 + 245819365.

It is an arithmetic number, because the mean of its divisors is an integer number (245819365).

Almost surely, 2^491638729 is an apocalyptic number.

It is an amenable number.

491638729 is a deficient number, since it is larger than the sum of its proper divisors (1).

491638729 is an equidigital number, since it uses as much as digits as its factorization.

491638729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 653184, while the sum is 49.

The square root of 491638729 is about 22172.9278400485. The cubic root of 491638729 is about 789.2514027007.

The spelling of 491638729 in words is "four hundred ninety-one million, six hundred thirty-eight thousand, seven hundred twenty-nine".