1665116491 has 2 divisors, whose sum is σ = 1665116492. Its totient is φ = 1665116490.

The previous prime is 1665116489. The next prime is 1665116501. The reversal of 1665116491 is 1946115661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1665116491 - 2¹ = 1665116489 is a prime.

It is a super-2 number, since 2×1665116491² = 5545225857200306162, which contains 22 as substring.

Together with 1665116489, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1665114491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832558245 + 832558246.

It is an arithmetic number, because the mean of its divisors is an integer number (832558246).

Almost surely, 2^1665116491 is an apocalyptic number.

1665116491 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665116491 is an equidigital number, since it uses as much as digits as its factorization.

1665116491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 40.

The square root of 1665116491 is about 40805.8389326822. The cubic root of 1665116491 is about 1185.2634001761.

The spelling of 1665116491 in words is "one billion, six hundred sixty-five million, one hundred sixteen thousand, four hundred ninety-one".