21081533 has 8 divisors (see below), whose sum is σ = 23322816. Its totient is φ = 18894400.

The previous prime is 21081517. The next prime is 21081551. The reversal of 21081533 is 33518012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21081533 - 2⁴ = 21081517 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21081499 and 21081508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081433) 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, 12716 + ... + 14277.

It is an arithmetic number, because the mean of its divisors is an integer number (2915352).

Almost surely, 2^21081533 is an apocalyptic number.

It is an amenable number.

21081533 is a deficient number, since it is larger than the sum of its proper divisors (2241283).

21081533 is a wasteful number, since it uses less digits than its factorization.

21081533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27075.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21081533 is about 4591.4630565866. The cubic root of 21081533 is about 276.2490095035.

Adding to 21081533 its reverse (33518012), we get a palindrome (54599545).

The spelling of 21081533 in words is "twenty-one million, eighty-one thousand, five hundred thirty-three".