21533012 has 6 divisors (see below), whose sum is σ = 37682778. Its totient is φ = 10766504.

The previous prime is 21533011. The next prime is 21533047. The reversal of 21533012 is 21033512.

It can be written as a sum of positive squares in only one way, i.e., 19324816 + 2208196 = 4396^2 + 1486^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2691623 + ... + 2691630.

It is an arithmetic number, because the mean of its divisors is an integer number (6280463).

Almost surely, 2^21533012 is an apocalyptic number.

It is an amenable number.

21533012 is a deficient number, since it is larger than the sum of its proper divisors (16149766).

21533012 is a wasteful number, since it uses less digits than its factorization.

21533012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5383257 (or 5383255 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 21533012 is about 4640.3676578478. The cubic root of 21533012 is about 278.2071330379.

Adding to 21533012 its reverse (21033512), we get a palindrome (42566524).

Subtracting from 21533012 its reverse (21033512), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 21533012 in words is "twenty-one million, five hundred thirty-three thousand, twelve".