1491967891 has 2 divisors, whose sum is σ = 1491967892. Its totient is φ = 1491967890.

The previous prime is 1491967871. The next prime is 1491967931. The reversal of 1491967891 is 1987691941.

It is a weak prime.

It is an emirp because it is prime and its reverse (1987691941) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1491967891 - 2¹¹ = 1491965843 is a prime.

It is not a weakly prime, because it can be changed into another prime (1491967811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 745983945 + 745983946.

It is an arithmetic number, because the mean of its divisors is an integer number (745983946).

Almost surely, 2^1491967891 is an apocalyptic number.

1491967891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1491967891 is an equidigital number, since it uses as much as digits as its factorization.

1491967891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 979776, while the sum is 55.

The square root of 1491967891 is about 38626.0001941697. Note that the first 3 decimals coincide. The cubic root of 1491967891 is about 1142.6673692432.

The spelling of 1491967891 in words is "one billion, four hundred ninety-one million, nine hundred sixty-seven thousand, eight hundred ninety-one".