21605034 has 24 divisors (see below), whose sum is σ = 47496960. Its totient is φ = 6546760.

The previous prime is 21605009. The next prime is 21605039. The reversal of 21605034 is 43050612.

It is a happy number.

It is a plaindrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 21605034.

It is not an unprimeable number, because it can be changed into a prime (21605039) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14154 + ... + 15605.

It is an arithmetic number, because the mean of its divisors is an integer number (1979040).

Almost surely, 2^21605034 is an apocalyptic number.

21605034 is an abundant number, since it is smaller than the sum of its proper divisors (25891926).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21605034 is a wasteful number, since it uses less digits than its factorization.

21605034 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29786 (or 29775 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21605034 is about 4648.1215560697. The cubic root of 21605034 is about 278.5169632976.

Adding to 21605034 its reverse (43050612), we get a palindrome (64655646).

The spelling of 21605034 in words is "twenty-one million, six hundred five thousand, thirty-four".