21573436 has 12 divisors (see below), whose sum is σ = 39740680. Its totient is φ = 10218960.

The previous prime is 21573413. The next prime is 21573437. The reversal of 21573436 is 63437512.

It is a junction number, because it is equal to n+sod(n) for n = 21573398 and 21573407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21573437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 141855 + ... + 142006.

Almost surely, 2^21573436 is an apocalyptic number.

It is an amenable number.

21573436 is a deficient number, since it is larger than the sum of its proper divisors (18167244).

21573436 is a wasteful number, since it uses less digits than its factorization.

21573436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283884 (or 283882 counting only the distinct ones).

The product of its digits is 15120, while the sum is 31.

The square root of 21573436 is about 4644.7213048793. The cubic root of 21573436 is about 278.3811172896.

The spelling of 21573436 in words is "twenty-one million, five hundred seventy-three thousand, four hundred thirty-six".