21212434 has 4 divisors (see below), whose sum is σ = 31818654. Its totient is φ = 10606216.

The previous prime is 21212431. The next prime is 21212449. The reversal of 21212434 is 43421212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 13344409 + 7868025 = 3653^2 + 2805^2 .

It is not an unprimeable number, because it can be changed into a prime (21212431) 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 as a sum of consecutive naturals, namely, 5303107 + ... + 5303110.

Almost surely, 2^21212434 is an apocalyptic number.

21212434 is a deficient number, since it is larger than the sum of its proper divisors (10606220).

21212434 is a wasteful number, since it uses less digits than its factorization.

21212434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10606219.

The product of its digits is 384, while the sum is 19.

The square root of 21212434 is about 4605.6958214802. The cubic root of 21212434 is about 276.8195986797.

Adding to 21212434 its reverse (43421212), we get a palindrome (64633646).

The spelling of 21212434 in words is "twenty-one million, two hundred twelve thousand, four hundred thirty-four".