43661819 has 4 divisors (see below), whose sum is σ = 43705200. Its totient is φ = 43618440.

The previous prime is 43661809. The next prime is 43661833. The reversal of 43661819 is 91816634.

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 43661819 - 2¹⁶ = 43596283 is a prime.

It is a super-2 number, since 2×43661819² = 3812708876777522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (43661809) 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, 20144 + ... + 22205.

It is an arithmetic number, because the mean of its divisors is an integer number (10926300).

Almost surely, 2^43661819 is an apocalyptic number.

43661819 is a deficient number, since it is larger than the sum of its proper divisors (43381).

43661819 is a wasteful number, since it uses less digits than its factorization.

43661819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43380.

The product of its digits is 31104, while the sum is 38.

The square root of 43661819 is about 6607.7090583651. The cubic root of 43661819 is about 352.1280391427.

The spelling of 43661819 in words is "forty-three million, six hundred sixty-one thousand, eight hundred nineteen".