1661665836 has 24 divisors (see below), whose sum is σ = 3877941760. Its totient is φ = 553785552.

The previous prime is 1661665781. The next prime is 1661665891. The reversal of 1661665836 is 6385661661.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1661665781) and next prime (1661665891).

It is a super-2 number, since 2×1661665836² = 5522266701059157792, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 82605 + ... + 100731.

Almost surely, 2^1661665836 is an apocalyptic number.

It is an amenable number.

1661665836 is an abundant number, since it is smaller than the sum of its proper divisors (2216275924).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661665836 is a wasteful number, since it uses less digits than its factorization.

1661665836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25773 (or 25771 counting only the distinct ones).

The product of its digits is 933120, while the sum is 48.

The square root of 1661665836 is about 40763.5356170193. The cubic root of 1661665836 is about 1184.4440854163. Note that the first 3 decimals are identical.

The spelling of 1661665836 in words is "one billion, six hundred sixty-one million, six hundred sixty-five thousand, eight hundred thirty-six".