1491188557 has 4 divisors (see below), whose sum is σ = 1492374240. Its totient is φ = 1490002876.

The previous prime is 1491188521. The next prime is 1491188563. The reversal of 1491188557 is 7558811941.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7558811941 = 953 ⋅7931597.

It is a cyclic number.

It is not a de Polignac number, because 1491188557 - 2¹⁵ = 1491155789 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1491188557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1491188057) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 590953 + ... + 593470.

It is an arithmetic number, because the mean of its divisors is an integer number (373093560).

Almost surely, 2^1491188557 is an apocalyptic number.

It is an amenable number.

1491188557 is a deficient number, since it is larger than the sum of its proper divisors (1185683).

1491188557 is a wasteful number, since it uses less digits than its factorization.

1491188557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1185682.

The product of its digits is 403200, while the sum is 49.

The square root of 1491188557 is about 38615.9106716390. The cubic root of 1491188557 is about 1142.4683759902.

The spelling of 1491188557 in words is "one billion, four hundred ninety-one million, one hundred eighty-eight thousand, five hundred fifty-seven".