1663543691 has 2 divisors, whose sum is σ = 1663543692. Its totient is φ = 1663543690.

The previous prime is 1663543681. The next prime is 1663543699. The reversal of 1663543691 is 1963453661.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1663543691 is a prime.

It is a super-2 number, since 2×1663543691² = 5534755223731806962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1663543699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 831771845 + 831771846.

It is an arithmetic number, because the mean of its divisors is an integer number (831771846).

Almost surely, 2^1663543691 is an apocalyptic number.

1663543691 is a deficient number, since it is larger than the sum of its proper divisors (1).

1663543691 is an equidigital number, since it uses as much as digits as its factorization.

1663543691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 349920, while the sum is 44.

The square root of 1663543691 is about 40786.5626279048. The cubic root of 1663543691 is about 1184.8900990613.

The spelling of 1663543691 in words is "one billion, six hundred sixty-three million, five hundred forty-three thousand, six hundred ninety-one".