21320634 has 16 divisors (see below), whose sum is σ = 42687072. Its totient is φ = 7099248.

The previous prime is 21320581. The next prime is 21320639. The reversal of 21320634 is 43602312.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21320634.

It is not an unprimeable number, because it can be changed into a prime (21320639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8577 + ... + 10779.

It is an arithmetic number, because the mean of its divisors is an integer number (2667942).

Almost surely, 2^21320634 is an apocalyptic number.

21320634 is an abundant number, since it is smaller than the sum of its proper divisors (21366438).

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

21320634 is a wasteful number, since it uses less digits than its factorization.

21320634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3821.

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 21320634 is about 4617.4272057067. The cubic root of 21320634 is about 277.2894661545.

Adding to 21320634 its reverse (43602312), we get a palindrome (64922946).

The spelling of 21320634 in words is "twenty-one million, three hundred twenty thousand, six hundred thirty-four".