21043730 has 16 divisors (see below), whose sum is σ = 39101184. Its totient is φ = 8145840.

The previous prime is 21043691. The next prime is 21043747. The reversal of 21043730 is 3734012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33632 + ... + 34251.

It is an arithmetic number, because the mean of its divisors is an integer number (2443824).

Almost surely, 2^21043730 is an apocalyptic number.

21043730 is a deficient number, since it is larger than the sum of its proper divisors (18057454).

21043730 is a wasteful number, since it uses less digits than its factorization.

21043730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67921.

The product of its (nonzero) digits is 504, while the sum is 20.

The square root of 21043730 is about 4587.3445477749. The cubic root of 21043730 is about 276.0837892351.

Adding to 21043730 its reverse (3734012), we get a palindrome (24777742).

The spelling of 21043730 in words is "twenty-one million, forty-three thousand, seven hundred thirty".