1661731199 has 4 divisors (see below), whose sum is σ = 1662103440. Its totient is φ = 1661358960.

The previous prime is 1661731177. The next prime is 1661731229. The reversal of 1661731199 is 9911371661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9911371661 = 2351 ⋅4215811.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661731199 is a prime.

It is a super-2 number, since 2×1661731199² = 5522701155459955202, 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 (1661731139) 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, 179342 + ... + 188379.

It is an arithmetic number, because the mean of its divisors is an integer number (415525860).

Almost surely, 2^1661731199 is an apocalyptic number.

1661731199 is a deficient number, since it is larger than the sum of its proper divisors (372241).

1661731199 is an equidigital number, since it uses as much as digits as its factorization.

1661731199 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372240.

The product of its digits is 61236, while the sum is 44.

The square root of 1661731199 is about 40764.3373428295. The cubic root of 1661731199 is about 1184.4596155752.

The spelling of 1661731199 in words is "one billion, six hundred sixty-one million, seven hundred thirty-one thousand, one hundred ninety-nine".