21212402 has 8 divisors (see below), whose sum is σ = 32419116. Its totient is φ = 10406032.

The previous prime is 21212353. The next prime is 21212423. The reversal of 21212402 is 20421212.

It can be written as a sum of positive squares in 2 ways, for example, as 19193161 + 2019241 = 4381^2 + 1421^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99953 + ... + 100164.

Almost surely, 2^21212402 is an apocalyptic number.

21212402 is a deficient number, since it is larger than the sum of its proper divisors (11206714).

21212402 is a wasteful number, since it uses less digits than its factorization.

21212402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200172.

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21212402 is about 4605.6923475195. The cubic root of 21212402 is about 276.8194594809.

Adding to 21212402 its reverse (20421212), we get a palindrome (41633614).

The spelling of 21212402 in words is "twenty-one million, two hundred twelve thousand, four hundred two".