21213634 has 16 divisors (see below), whose sum is σ = 34345080. Its totient is φ = 9768960.

The previous prime is 21213631. The next prime is 21213667. The reversal of 21213634 is 43631212.

It can be written as a sum of positive squares in 4 ways, for example, as 15186609 + 6027025 = 3897^2 + 2455^2 .

It is not an unprimeable number, because it can be changed into a prime (21213631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19464 + ... + 20524.

Almost surely, 2^21213634 is an apocalyptic number.

21213634 is a deficient number, since it is larger than the sum of its proper divisors (13131446).

21213634 is a wasteful number, since it uses less digits than its factorization.

21213634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1845.

The product of its digits is 864, while the sum is 22.

The square root of 21213634 is about 4605.8260931129. The cubic root of 21213634 is about 276.8248185310.

Adding to 21213634 its reverse (43631212), we get a palindrome (64844846).

The spelling of 21213634 in words is "twenty-one million, two hundred thirteen thousand, six hundred thirty-four".