1491445691 has 4 divisors (see below), whose sum is σ = 1531755072. Its totient is φ = 1451136312.

The previous prime is 1491445663. The next prime is 1491445733. The reversal of 1491445691 is 1965441941.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1965441941 = 193 ⋅10183637.

It is a cyclic number.

It is not a de Polignac number, because 1491445691 - 2¹⁴ = 1491429307 is a prime.

It is a super-3 number, since 3×1491445691³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1491445621) 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 in 3 ways as a sum of consecutive naturals, for example, 20154635 + ... + 20154708.

It is an arithmetic number, because the mean of its divisors is an integer number (382938768).

Almost surely, 2^1491445691 is an apocalyptic number.

1491445691 is a deficient number, since it is larger than the sum of its proper divisors (40309381).

1491445691 is an equidigital number, since it uses as much as digits as its factorization.

1491445691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40309380.

The product of its digits is 155520, while the sum is 44.

The square root of 1491445691 is about 38619.2399070722. The cubic root of 1491445691 is about 1142.5340396244.

The spelling of 1491445691 in words is "one billion, four hundred ninety-one million, four hundred forty-five thousand, six hundred ninety-one".