21042650 has 12 divisors (see below), whose sum is σ = 39139422. Its totient is φ = 8417040.

The previous prime is 21042649. The next prime is 21042689. The reversal of 21042650 is 5624012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 18395521 + 2647129 = 4289^2 + 1627^2 .

It is a Curzon 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 in 5 ways as a sum of consecutive naturals, for example, 210377 + ... + 210476.

Almost surely, 2^21042650 is an apocalyptic number.

21042650 is a deficient number, since it is larger than the sum of its proper divisors (18096772).

21042650 is a wasteful number, since it uses less digits than its factorization.

21042650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 420865 (or 420860 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21042650 is about 4587.2268311040. The cubic root of 21042650 is about 276.0790661245.

Adding to 21042650 its reverse (5624012), we get a palindrome (26666662).

The spelling of 21042650 in words is "twenty-one million, forty-two thousand, six hundred fifty".