21020212 has 6 divisors (see below), whose sum is σ = 36785378. Its totient is φ = 10510104.

The previous prime is 21020161. The next prime is 21020227. The reversal of 21020212 is 21202012.

It can be written as a sum of positive squares in only one way, i.e., 17943696 + 3076516 = 4236^2 + 1754^2 .

It is a congruent number.

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, 2627523 + ... + 2627530.

Almost surely, 2^21020212 is an apocalyptic number.

It is an amenable number.

21020212 is a deficient number, since it is larger than the sum of its proper divisors (15765166).

21020212 is a wasteful number, since it uses less digits than its factorization.

21020212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5255057 (or 5255055 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21020212 is about 4584.7804745702. The cubic root of 21020212 is about 275.9809025503.

Adding to 21020212 its reverse (21202012), we get a palindrome (42222224).

The spelling of 21020212 in words is "twenty-one million, twenty thousand, two hundred twelve".