21212534 has 16 divisors (see below), whose sum is σ = 36612000. Its totient is φ = 9029184.

The previous prime is 21212519. The next prime is 21212537. The reversal of 21212534 is 43521212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212537) 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, 2999 + ... + 7170.

It is an arithmetic number, because the mean of its divisors is an integer number (2288250).

Almost surely, 2^21212534 is an apocalyptic number.

21212534 is a deficient number, since it is larger than the sum of its proper divisors (15399466).

21212534 is a wasteful number, since it uses less digits than its factorization.

21212534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10327.

The product of its digits is 480, while the sum is 20.

The square root of 21212534 is about 4605.7066775903. The cubic root of 21212534 is about 276.8200336748.

Adding to 21212534 its reverse (43521212), we get a palindrome (64733746).

The spelling of 21212534 in words is "twenty-one million, two hundred twelve thousand, five hundred thirty-four".