21213534 has 16 divisors (see below), whose sum is σ = 43414272. Its totient is φ = 6906648.

The previous prime is 21213487. The next prime is 21213553. The reversal of 21213534 is 43531212.

It is a self number, because there is not a number n which added to its sum of digits gives 21213534.

It is a congruent number.

It is an unprimeable number.

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, 40854 + ... + 41369.

It is an arithmetic number, because the mean of its divisors is an integer number (2713392).

Almost surely, 2^21213534 is an apocalyptic number.

21213534 is an abundant number, since it is smaller than the sum of its proper divisors (22200738).

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

21213534 is a wasteful number, since it uses less digits than its factorization.

21213534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82271.

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

The square root of 21213534 is about 4605.8152372843. The cubic root of 21213534 is about 276.8243835509.

Adding to 21213534 its reverse (43531212), we get a palindrome (64744746).

The spelling of 21213534 in words is "twenty-one million, two hundred thirteen thousand, five hundred thirty-four".