1663245491 has 4 divisors (see below), whose sum is σ = 1663526592. Its totient is φ = 1662964392.

The previous prime is 1663245431. The next prime is 1663245509. The reversal of 1663245491 is 1945423661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1945423661 = 19 ⋅102390719.

It is a cyclic number.

It is not a de Polignac number, because 1663245491 - 2¹⁸ = 1662983347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1663245421) 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, 131480 + ... + 143573.

It is an arithmetic number, because the mean of its divisors is an integer number (415881648).

Almost surely, 2^1663245491 is an apocalyptic number.

1663245491 is a deficient number, since it is larger than the sum of its proper divisors (281101).

1663245491 is an equidigital number, since it uses as much as digits as its factorization.

1663245491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281100.

The product of its digits is 155520, while the sum is 41.

The square root of 1663245491 is about 40782.9068483354. The cubic root of 1663245491 is about 1184.8192953219.

The spelling of 1663245491 in words is "one billion, six hundred sixty-three million, two hundred forty-five thousand, four hundred ninety-one".