21654212 has 6 divisors (see below), whose sum is σ = 37894878. Its totient is φ = 10827104.

The previous prime is 21654203. The next prime is 21654223. The reversal of 21654212 is 21245612.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20921476 + 732736 = 4574^2 + 856^2 .

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 as a sum of consecutive naturals, namely, 2706773 + ... + 2706780.

It is an arithmetic number, because the mean of its divisors is an integer number (6315813).

Almost surely, 2^21654212 is an apocalyptic number.

It is an amenable number.

21654212 is a deficient number, since it is larger than the sum of its proper divisors (16240666).

21654212 is a wasteful number, since it uses less digits than its factorization.

21654212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5413557 (or 5413555 counting only the distinct ones).

The product of its digits is 960, while the sum is 23.

The square root of 21654212 is about 4653.4086431346. The cubic root of 21654212 is about 278.7281259354.

Adding to 21654212 its reverse (21245612), we get a palindrome (42899824).

The spelling of 21654212 in words is "twenty-one million, six hundred fifty-four thousand, two hundred twelve".