43400021 has 4 divisors (see below), whose sum is σ = 49600032. Its totient is φ = 37200012.

The previous prime is 43399973. The next prime is 43400051. The reversal of 43400021 is 12000434.

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 a de Polignac number, because none of the positive numbers 2^k-43400021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 43399969 and 43400005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (43400051) 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, 3099995 + ... + 3100008.

It is an arithmetic number, because the mean of its divisors is an integer number (12400008).

Almost surely, 2^43400021 is an apocalyptic number.

It is an amenable number.

43400021 is a deficient number, since it is larger than the sum of its proper divisors (6200011).

43400021 is an equidigital number, since it uses as much as digits as its factorization.

43400021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6200010.

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 43400021 is about 6587.8692306390. The cubic root of 43400021 is about 351.4228365510.

Adding to 43400021 its reverse (12000434), we get a palindrome (55400455).

The spelling of 43400021 in words is "forty-three million, four hundred thousand, twenty-one".