21355533 has 6 divisors (see below), whose sum is σ = 30846894. Its totient is φ = 14237016.

The previous prime is 21355511. The next prime is 21355561. The reversal of 21355533 is 33555312.

It can be written as a sum of positive squares in only one way, i.e., 13638249 + 7717284 = 3693^2 + 2778^2 .

It is not a de Polignac number, because 21355533 - 2⁵ = 21355501 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21355497 and 21355506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355573) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1186410 + ... + 1186427.

It is an arithmetic number, because the mean of its divisors is an integer number (5141149).

Almost surely, 2^21355533 is an apocalyptic number.

It is an amenable number.

21355533 is a deficient number, since it is larger than the sum of its proper divisors (9491361).

21355533 is a wasteful number, since it uses less digits than its factorization.

21355533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2372843 (or 2372840 counting only the distinct ones).

The product of its digits is 6750, while the sum is 27.

The square root of 21355533 is about 4621.2047130591. The cubic root of 21355533 is about 277.4406788221.

The spelling of 21355533 in words is "twenty-one million, three hundred fifty-five thousand, five hundred thirty-three".