491481389251 has 2 divisors, whose sum is σ = 491481389252. Its totient is φ = 491481389250.

The previous prime is 491481389249. The next prime is 491481389257. The reversal of 491481389251 is 152983184194.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 491481389251 - 2¹ = 491481389249 is a prime.

Together with 491481389249, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 491481389192 and 491481389201.

It is not a weakly prime, because it can be changed into another prime (491481389257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245740694625 + 245740694626.

It is an arithmetic number, because the mean of its divisors is an integer number (245740694626).

Almost surely, 2^491481389251 is an apocalyptic number.

491481389251 is a deficient number, since it is larger than the sum of its proper divisors (1).

491481389251 is an equidigital number, since it uses as much as digits as its factorization.

491481389251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2488320, while the sum is 55.

The spelling of 491481389251 in words is "four hundred ninety-one billion, four hundred eighty-one million, three hundred eighty-nine thousand, two hundred fifty-one".