43690721 has 2 divisors, whose sum is σ = 43690722. Its totient is φ = 43690720.

The previous prime is 43690693. The next prime is 43690729. The reversal of 43690721 is 12709634.

43690721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41473600 + 2217121 = 6440^2 + 1489^2 .

It is a cyclic number.

It is not a de Polignac number, because 43690721 - 2⁶ = 43690657 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (43690729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21845360 + 21845361.

It is an arithmetic number, because the mean of its divisors is an integer number (21845361).

Almost surely, 2^43690721 is an apocalyptic number.

It is an amenable number.

43690721 is a deficient number, since it is larger than the sum of its proper divisors (1).

43690721 is an equidigital number, since it uses as much as digits as its factorization.

43690721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 43690721 is about 6609.8956875279. The cubic root of 43690721 is about 352.2057192153.

The spelling of 43690721 in words is "forty-three million, six hundred ninety thousand, seven hundred twenty-one".