43131721 has 4 divisors (see below), whose sum is σ = 43145092. Its totient is φ = 43118352.

The previous prime is 43131701. The next prime is 43131727. The reversal of 43131721 is 12713134.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 18181696 + 24950025 = 4264^2 + 4995^2 .

It is a cyclic number.

It is not a de Polignac number, because 43131721 - 2⁵ = 43131689 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 43131692 and 43131701.

It is not an unprimeable number, because it can be changed into a prime (43131727) 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, 1471 + ... + 9403.

It is an arithmetic number, because the mean of its divisors is an integer number (10786273).

Almost surely, 2^43131721 is an apocalyptic number.

It is an amenable number.

43131721 is a deficient number, since it is larger than the sum of its proper divisors (13371).

43131721 is an equidigital number, since it uses as much as digits as its factorization.

43131721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13370.

The product of its digits is 504, while the sum is 22.

The square root of 43131721 is about 6567.4744765397. The cubic root of 43131721 is about 350.6971709156.

Adding to 43131721 its reverse (12713134), we get a palindrome (55844855).

The spelling of 43131721 in words is "forty-three million, one hundred thirty-one thousand, seven hundred twenty-one".