1491187813 has 2 divisors, whose sum is σ = 1491187814. Its totient is φ = 1491187812.

The previous prime is 1491187787. The next prime is 1491187829. The reversal of 1491187813 is 3187811941.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 860072929 + 631114884 = 29327^2 + 25122^2 .

It is a cyclic number.

It is not a de Polignac number, because 1491187813 - 2⁹ = 1491187301 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1491187813.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1491287813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 745593906 + 745593907.

It is an arithmetic number, because the mean of its divisors is an integer number (745593907).

Almost surely, 2^1491187813 is an apocalyptic number.

It is an amenable number.

1491187813 is a deficient number, since it is larger than the sum of its proper divisors (1).

1491187813 is an equidigital number, since it uses as much as digits as its factorization.

1491187813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 43.

The square root of 1491187813 is about 38615.9010383029. The cubic root of 1491187813 is about 1142.4681859860.

The spelling of 1491187813 in words is "one billion, four hundred ninety-one million, one hundred eighty-seven thousand, eight hundred thirteen".