21036538 has 16 divisors (see below), whose sum is σ = 32820480. Its totient is φ = 10101600.

The previous prime is 21036527. The next prime is 21036539. The reversal of 21036538 is 83563012.

It is not an unprimeable number, because it can be changed into a prime (21036539) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7398 + ... + 9838.

It is an arithmetic number, because the mean of its divisors is an integer number (2051280).

Almost surely, 2^21036538 is an apocalyptic number.

21036538 is a deficient number, since it is larger than the sum of its proper divisors (11783942).

21036538 is a wasteful number, since it uses less digits than its factorization.

21036538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2613.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21036538 is about 4586.5605850136. The cubic root of 21036538 is about 276.0523337714.

The spelling of 21036538 in words is "twenty-one million, thirty-six thousand, five hundred thirty-eight".