21400443 has 20 divisors (see below), whose sum is σ = 32095008. Its totient is φ = 14210640.

The previous prime is 21400429. The next prime is 21400451. The reversal of 21400443 is 34400412.

It is not a de Polignac number, because 21400443 - 2¹³ = 21392251 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21400453) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 34605 + ... + 35217.

Almost surely, 2^21400443 is an apocalyptic number.

21400443 is a deficient number, since it is larger than the sum of its proper divisors (10694565).

21400443 is an equidigital number, since it uses as much as digits as its factorization.

21400443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1056 (or 1047 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21400443 is about 4626.0612836408. The cubic root of 21400443 is about 277.6350255963.

Adding to 21400443 its reverse (34400412), we get a palindrome (55800855).

The spelling of 21400443 in words is "twenty-one million, four hundred thousand, four hundred forty-three".