1661812197 has 8 divisors (see below), whose sum is σ = 2237262144. Its totient is φ = 1097118528.

The previous prime is 1661812151. The next prime is 1661812247. The reversal of 1661812197 is 7912181661.

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

It is not a de Polignac number, because 1661812197 - 2⁷ = 1661812069 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661814197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2688708 + ... + 2689325.

It is an arithmetic number, because the mean of its divisors is an integer number (279657768).

Almost surely, 2^1661812197 is an apocalyptic number.

It is an amenable number.

1661812197 is a deficient number, since it is larger than the sum of its proper divisors (575449947).

1661812197 is a wasteful number, since it uses less digits than its factorization.

1661812197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5378139.

The product of its digits is 36288, while the sum is 42.

The square root of 1661812197 is about 40765.3308216676. The cubic root of 1661812197 is about 1184.4788600237.

The spelling of 1661812197 in words is "one billion, six hundred sixty-one million, eight hundred twelve thousand, one hundred ninety-seven".