21212042 has 4 divisors (see below), whose sum is σ = 31818066. Its totient is φ = 10606020.

The previous prime is 21212033. The next prime is 21212071. The reversal of 21212042 is 24021212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20620681 + 591361 = 4541^2 + 769^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5303009 + ... + 5303012.

Almost surely, 2^21212042 is an apocalyptic number.

21212042 is a deficient number, since it is larger than the sum of its proper divisors (10606024).

21212042 is a wasteful number, since it uses less digits than its factorization.

21212042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10606023.

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

The square root of 21212042 is about 4605.6532652817. The cubic root of 21212042 is about 276.8178934856.

Adding to 21212042 its reverse (24021212), we get a palindrome (45233254).

The spelling of 21212042 in words is "twenty-one million, two hundred twelve thousand, forty-two".