21217834 has 24 divisors (see below), whose sum is σ = 35814240. Its totient is φ = 9415560.

The previous prime is 21217829. The next prime is 21217837. The reversal of 21217834 is 43871212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21217837) 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, 9387 + ... + 11425.

It is an arithmetic number, because the mean of its divisors is an integer number (1492260).

Almost surely, 2^21217834 is an apocalyptic number.

21217834 is a deficient number, since it is larger than the sum of its proper divisors (14596406).

21217834 is a wasteful number, since it uses less digits than its factorization.

21217834 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2106 (or 2095 counting only the distinct ones).

The product of its digits is 2688, while the sum is 28.

The square root of 21217834 is about 4606.2820148141. The cubic root of 21217834 is about 276.8430864606.

It can be divided in two parts, 212178 and 34, that added together give a palindrome (212212).

The spelling of 21217834 in words is "twenty-one million, two hundred seventeen thousand, eight hundred thirty-four".