21043016 has 8 divisors (see below), whose sum is σ = 39455670. Its totient is φ = 10521504.

The previous prime is 21043007. The next prime is 21043019. The reversal of 21043016 is 61034012.

It can be written as a sum of positive squares in only one way, i.e., 11764900 + 9278116 = 3430^2 + 3046^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21042985 and 21043003.

It is not an unprimeable number, because it can be changed into a prime (21043019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1315181 + ... + 1315196.

Almost surely, 2^21043016 is an apocalyptic number.

It is an amenable number.

21043016 is a deficient number, since it is larger than the sum of its proper divisors (18412654).

21043016 is a wasteful number, since it uses less digits than its factorization.

21043016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2630383 (or 2630379 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21043016 is about 4587.2667243142. The cubic root of 21043016 is about 276.0806667523.

Adding to 21043016 its reverse (61034012), we get a palindrome (82077028).

The spelling of 21043016 in words is "twenty-one million, forty-three thousand, sixteen".