21398434 has 16 divisors (see below), whose sum is σ = 33390720. Its totient is φ = 10276560.

The previous prime is 21398423. The next prime is 21398437. The reversal of 21398434 is 43489312.

It is a self number, because there is not a number n which added to its sum of digits gives 21398434.

It is not an unprimeable number, because it can be changed into a prime (21398437) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3207 + ... + 7285.

It is an arithmetic number, because the mean of its divisors is an integer number (2086920).

Almost surely, 2^21398434 is an apocalyptic number.

21398434 is a deficient number, since it is larger than the sum of its proper divisors (11992286).

21398434 is a wasteful number, since it uses less digits than its factorization.

21398434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4185.

The product of its digits is 20736, while the sum is 34.

The square root of 21398434 is about 4625.8441391815. The cubic root of 21398434 is about 277.6263375172.

The spelling of 21398434 in words is "twenty-one million, three hundred ninety-eight thousand, four hundred thirty-four".