43021721 has 4 divisors (see below), whose sum is σ = 43211472. Its totient is φ = 42831972.

The previous prime is 43021717. The next prime is 43021729. The reversal of 43021721 is 12712034.

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 not a de Polignac number, because 43021721 - 2² = 43021717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 43021693 and 43021702.

It is not an unprimeable number, because it can be changed into a prime (43021729) 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, 94535 + ... + 94988.

It is an arithmetic number, because the mean of its divisors is an integer number (10802868).

Almost surely, 2^43021721 is an apocalyptic number.

It is an amenable number.

43021721 is a deficient number, since it is larger than the sum of its proper divisors (189751).

43021721 is a wasteful number, since it uses less digits than its factorization.

43021721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189750.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 43021721 is about 6559.0945259235. The cubic root of 43021721 is about 350.3987862709.

Adding to 43021721 its reverse (12712034), we get a palindrome (55733755).

The spelling of 43021721 in words is "forty-three million, twenty-one thousand, seven hundred twenty-one".