43666681 has 4 divisors (see below), whose sum is σ = 44731764. Its totient is φ = 42601600.

The previous prime is 43666657. The next prime is 43666687. The reversal of 43666681 is 18666634.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6456681 + 37210000 = 2541^2 + 6100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43666681 is a prime.

It is a super-2 number, since 2×43666681² = 3813558059111522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (43666687) 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, 532480 + ... + 532561.

It is an arithmetic number, because the mean of its divisors is an integer number (11182941).

Almost surely, 2^43666681 is an apocalyptic number.

43666681 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

It is an amenable number.

43666681 is a deficient number, since it is larger than the sum of its proper divisors (1065083).

43666681 is a wasteful number, since it uses less digits than its factorization.

43666681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1065082.

The product of its digits is 124416, while the sum is 40.

The square root of 43666681 is about 6608.0769517311. The cubic root of 43666681 is about 352.1411091661.

The spelling of 43666681 in words is "forty-three million, six hundred sixty-six thousand, six hundred eighty-one".