21018412 has 12 divisors (see below), whose sum is σ = 38381616. Its totient is φ = 10052240.

The previous prime is 21018407. The next prime is 21018461. The reversal of 21018412 is 21481012.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21018412.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 114139 + ... + 114322.

It is an arithmetic number, because the mean of its divisors is an integer number (3198468).

Almost surely, 2^21018412 is an apocalyptic number.

It is an amenable number.

21018412 is a deficient number, since it is larger than the sum of its proper divisors (17363204).

21018412 is a wasteful number, since it uses less digits than its factorization.

21018412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228488 (or 228486 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 21018412 is about 4584.5841687115. The cubic root of 21018412 is about 275.9730247388.

Adding to 21018412 its reverse (21481012), we get a palindrome (42499424).

The spelling of 21018412 in words is "twenty-one million, eighteen thousand, four hundred twelve".