1668637091 has 8 divisors (see below), whose sum is σ = 1927409904. Its totient is φ = 1427710720.

The previous prime is 1668637049. The next prime is 1668637141. The reversal of 1668637091 is 1907368661.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1668637091 - 2¹⁸ = 1668374947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1668637991) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4461410 + ... + 4461783.

It is an arithmetic number, because the mean of its divisors is an integer number (240926238).

Almost surely, 2^1668637091 is an apocalyptic number.

1668637091 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1668637091 is a deficient number, since it is larger than the sum of its proper divisors (258772813).

1668637091 is a wasteful number, since it uses less digits than its factorization.

1668637091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8923221.

The product of its (nonzero) digits is 326592, while the sum is 47.

The square root of 1668637091 is about 40848.9545888264. The cubic root of 1668637091 is about 1186.0981567602.

The spelling of 1668637091 in words is "one billion, six hundred sixty-eight million, six hundred thirty-seven thousand, ninety-one".