1491868817 has 2 divisors, whose sum is σ = 1491868818. Its totient is φ = 1491868816.

The previous prime is 1491868799. The next prime is 1491868841. The reversal of 1491868817 is 7188681941.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1465664656 + 26204161 = 38284^2 + 5119^2 .

It is a cyclic number.

It is not a de Polignac number, because 1491868817 - 2⁸ = 1491868561 is a prime.

It is not a weakly prime, because it can be changed into another prime (1491864817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 745934408 + 745934409.

It is an arithmetic number, because the mean of its divisors is an integer number (745934409).

Almost surely, 2^1491868817 is an apocalyptic number.

It is an amenable number.

1491868817 is a deficient number, since it is larger than the sum of its proper divisors (1).

1491868817 is an equidigital number, since it uses as much as digits as its factorization.

1491868817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 774144, while the sum is 53.

The square root of 1491868817 is about 38624.7176947612. The cubic root of 1491868817 is about 1142.6420757737.

The spelling of 1491868817 in words is "one billion, four hundred ninety-one million, eight hundred sixty-eight thousand, eight hundred seventeen".