21533129 has 4 divisors (see below), whose sum is σ = 22469376. Its totient is φ = 20596884.

The previous prime is 21533123. The next prime is 21533131. The reversal of 21533129 is 92133512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21533129 - 2⁸ = 21532873 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a zygodrome in base 3.

It is a junction number, because it is equal to n+sod(n) for n = 21533098 and 21533107.

It is not an unprimeable number, because it can be changed into a prime (21533123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 468089 + ... + 468134.

It is an arithmetic number, because the mean of its divisors is an integer number (5617344).

Almost surely, 2^21533129 is an apocalyptic number.

It is an amenable number.

21533129 is a deficient number, since it is larger than the sum of its proper divisors (936247).

21533129 is an equidigital number, since it uses as much as digits as its factorization.

21533129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 936246.

The product of its digits is 1620, while the sum is 26.

The square root of 21533129 is about 4640.3802645904. The cubic root of 21533129 is about 278.2076369181.

The spelling of 21533129 in words is "twenty-one million, five hundred thirty-three thousand, one hundred twenty-nine".