1865161491 has 4 divisors (see below), whose sum is σ = 2486881992. Its totient is φ = 1243440992.

The previous prime is 1865161483. The next prime is 1865161523. The reversal of 1865161491 is 1941615681.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1865161491 - 2³ = 1865161483 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1865162491) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 310860246 + ... + 310860251.

It is an arithmetic number, because the mean of its divisors is an integer number (621720498).

Almost surely, 2^1865161491 is an apocalyptic number.

1865161491 is a deficient number, since it is larger than the sum of its proper divisors (621720501).

1865161491 is an equidigital number, since it uses as much as digits as its factorization.

1865161491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621720500.

The product of its digits is 51840, while the sum is 42.

The square root of 1865161491 is about 43187.5154529640. The cubic root of 1865161491 is about 1230.9454671236.

The spelling of 1865161491 in words is "one billion, eight hundred sixty-five million, one hundred sixty-one thousand, four hundred ninety-one".