43418591621 has 2 divisors, whose sum is σ = 43418591622. Its totient is φ = 43418591620.

The previous prime is 43418591609. The next prime is 43418591707. The reversal of 43418591621 is 12619581434.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42317015521 + 1101576100 = 205711^2 + 33190^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-43418591621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (43418591221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21709295810 + 21709295811.

It is an arithmetic number, because the mean of its divisors is an integer number (21709295811).

Almost surely, 2^43418591621 is an apocalyptic number.

It is an amenable number.

43418591621 is a deficient number, since it is larger than the sum of its proper divisors (1).

43418591621 is an equidigital number, since it uses as much as digits as its factorization.

43418591621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 207360, while the sum is 44.

The spelling of 43418591621 in words is "forty-three billion, four hundred eighteen million, five hundred ninety-one thousand, six hundred twenty-one".