1663491 has 12 divisors (see below), whose sum is σ = 2295816. Its totient is φ = 1071360.

The previous prime is 1663481. The next prime is 1663513. The reversal of 1663491 is 1943661.

It is not a de Polignac number, because 1663491 - 2⁹ = 1662979 is a prime.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1663481) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2595 + ... + 3171.

It is an arithmetic number, because the mean of its divisors is an integer number (191318).

2^1663491 is an apocalyptic number.

1663491 is a deficient number, since it is larger than the sum of its proper divisors (632325).

1663491 is an equidigital number, since it uses as much as digits as its factorization.

1663491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642 (or 611 counting only the distinct ones).

The product of its digits is 3888, while the sum is 30.

The square root of 1663491 is about 1289.7639318883. The cubic root of 1663491 is about 118.4877588879.

The spelling of 1663491 in words is "one million, six hundred sixty-three thousand, four hundred ninety-one".