21043930 has 16 divisors (see below), whose sum is σ = 38248704. Its totient is φ = 8335440.

The previous prime is 21043927. The next prime is 21043949. The reversal of 21043930 is 3934012.

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 7 ways as a sum of consecutive naturals, for example, 9186 + ... + 11245.

It is an arithmetic number, because the mean of its divisors is an integer number (2390544).

Almost surely, 2^21043930 is an apocalyptic number.

21043930 is a deficient number, since it is larger than the sum of its proper divisors (17204774).

21043930 is a wasteful number, since it uses less digits than its factorization.

21043930 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20541.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 21043930 is about 4587.3663468269. The cubic root of 21043930 is about 276.0846638675.

Adding to 21043930 its reverse (3934012), we get a palindrome (24977942).

The spelling of 21043930 in words is "twenty-one million, forty-three thousand, nine hundred thirty".