1664618191 has 4 divisors (see below), whose sum is σ = 1718315584. Its totient is φ = 1610920800.

The previous prime is 1664618173. The next prime is 1664618213. The reversal of 1664618191 is 1918164661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1664618191 - 2¹¹ = 1664616143 is a prime.

It is a super-2 number, since 2×1664618191² = 5541907443616224962, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664618141) 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, 26848650 + ... + 26848711.

It is an arithmetic number, because the mean of its divisors is an integer number (429578896).

Almost surely, 2^1664618191 is an apocalyptic number.

1664618191 is a deficient number, since it is larger than the sum of its proper divisors (53697393).

1664618191 is an equidigital number, since it uses as much as digits as its factorization.

1664618191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53697392.

The product of its digits is 62208, while the sum is 43.

The square root of 1664618191 is about 40799.7327319677. The cubic root of 1664618191 is about 1185.1451550602.

The spelling of 1664618191 in words is "one billion, six hundred sixty-four million, six hundred eighteen thousand, one hundred ninety-one".