21221634 has 16 divisors (see below), whose sum is σ = 48506688. Its totient is φ = 6063312.

The previous prime is 21221633. The next prime is 21221653. The reversal of 21221634 is 43612212.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 21221634.

It is not an unprimeable number, because it can be changed into a prime (21221633) 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, 252597 + ... + 252680.

It is an arithmetic number, because the mean of its divisors is an integer number (3031668).

Almost surely, 2^21221634 is an apocalyptic number.

21221634 is an abundant number, since it is smaller than the sum of its proper divisors (27285054).

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

21221634 is a wasteful number, since it uses less digits than its factorization.

21221634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 505289.

The product of its digits is 576, while the sum is 21.

The square root of 21221634 is about 4606.6944765200. The cubic root of 21221634 is about 276.8596125102.

Adding to 21221634 its reverse (43612212), we get a palindrome (64833846).

The spelling of 21221634 in words is "twenty-one million, two hundred twenty-one thousand, six hundred thirty-four".