21212734 has 4 divisors (see below), whose sum is σ = 31819104. Its totient is φ = 10606366.

The previous prime is 21212731. The next prime is 21212749. The reversal of 21212734 is 43721212.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5303182 + ... + 5303185.

It is an arithmetic number, because the mean of its divisors is an integer number (7954776).

Almost surely, 2^21212734 is an apocalyptic number.

21212734 is a deficient number, since it is larger than the sum of its proper divisors (10606370).

21212734 is a wasteful number, since it uses less digits than its factorization.

21212734 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10606369.

The product of its digits is 672, while the sum is 22.

The square root of 21212734 is about 4605.7283897338. The cubic root of 21212734 is about 276.8209036610.

Adding to 21212734 its reverse (43721212), we get a palindrome (64933946).

The spelling of 21212734 in words is "twenty-one million, two hundred twelve thousand, seven hundred thirty-four".