21212746 has 16 divisors (see below), whose sum is σ = 33027840. Its totient is φ = 10206000.

The previous prime is 21212731. The next prime is 21212749. The reversal of 21212746 is 64721212.

It is a self number, because there is not a number n which added to its sum of digits gives 21212746.

It is not an unprimeable number, because it can be changed into a prime (21212749) 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, 27871 + ... + 28621.

It is an arithmetic number, because the mean of its divisors is an integer number (2064240).

Almost surely, 2^21212746 is an apocalyptic number.

21212746 is a deficient number, since it is larger than the sum of its proper divisors (11815094).

21212746 is a wasteful number, since it uses less digits than its factorization.

21212746 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1269.

The product of its digits is 1344, while the sum is 25.

The square root of 21212746 is about 4605.7296924592. The cubic root of 21212746 is about 276.8209558600.

Adding to 21212746 its reverse (64721212), we get a palindrome (85933958).

The spelling of 21212746 in words is "twenty-one million, two hundred twelve thousand, seven hundred forty-six".