43537721 has 4 divisors (see below), whose sum is σ = 45829200. Its totient is φ = 41246244.

The previous prime is 43537691. The next prime is 43537757. The reversal of 43537721 is 12773534.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43537721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (43536721) 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, 1145711 + ... + 1145748.

It is an arithmetic number, because the mean of its divisors is an integer number (11457300).

Almost surely, 2^43537721 is an apocalyptic number.

It is an amenable number.

43537721 is a deficient number, since it is larger than the sum of its proper divisors (2291479).

43537721 is a wasteful number, since it uses less digits than its factorization.

43537721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2291478.

The product of its digits is 17640, while the sum is 32.

The square root of 43537721 is about 6598.3119811055. The cubic root of 43537721 is about 351.7941100750.

The spelling of 43537721 in words is "forty-three million, five hundred thirty-seven thousand, seven hundred twenty-one".