43665421 has 2 divisors, whose sum is σ = 43665422. Its totient is φ = 43665420.

The previous prime is 43665409. The next prime is 43665437. The reversal of 43665421 is 12456634.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43494025 + 171396 = 6595^2 + 414^2 .

It is a cyclic number.

It is not a de Polignac number, because 43665421 - 2⁵ = 43665389 is a prime.

It is a super-2 number, since 2×43665421² = 3813337982214482, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (43665821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21832710 + 21832711.

It is an arithmetic number, because the mean of its divisors is an integer number (21832711).

Almost surely, 2^43665421 is an apocalyptic number.

It is an amenable number.

43665421 is a deficient number, since it is larger than the sum of its proper divisors (1).

43665421 is an equidigital number, since it uses as much as digits as its factorization.

43665421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 31.

The square root of 43665421 is about 6607.9816131705. The cubic root of 43665421 is about 352.1377221285.

The spelling of 43665421 in words is "forty-three million, six hundred sixty-five thousand, four hundred twenty-one".