21212552 has 8 divisors (see below), whose sum is σ = 39773550. Its totient is φ = 10606272.

The previous prime is 21212537. The next prime is 21212591. The reversal of 21212552 is 25521212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 19589476 + 1623076 = 4426^2 + 1274^2 .

It is a tau number, because it is divible by the number of its divisors (8).

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, 1325777 + ... + 1325792.

Almost surely, 2^21212552 is an apocalyptic number.

It is an amenable number.

21212552 is a deficient number, since it is larger than the sum of its proper divisors (18560998).

21212552 is a wasteful number, since it uses less digits than its factorization.

21212552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2651575 (or 2651571 counting only the distinct ones).

The product of its digits is 400, while the sum is 20.

The square root of 21212552 is about 4605.7086316874. The cubic root of 21212552 is about 276.8201119738.

Adding to 21212552 its reverse (25521212), we get a palindrome (46733764).

The spelling of 21212552 in words is "twenty-one million, two hundred twelve thousand, five hundred fifty-two".