21533613 has 8 divisors (see below), whose sum is σ = 29105088. Its totient is φ = 14158944.

The previous prime is 21533597. The next prime is 21533647. The reversal of 21533613 is 31633512.

It is a happy number.

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

It is not a de Polignac number, because 21533613 - 2⁴ = 21533597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533683) 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, 48945 + ... + 49382.

It is an arithmetic number, because the mean of its divisors is an integer number (3638136).

Almost surely, 2^21533613 is an apocalyptic number.

It is an amenable number.

21533613 is a deficient number, since it is larger than the sum of its proper divisors (7571475).

21533613 is an equidigital number, since it uses as much as digits as its factorization.

21533613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98403.

The product of its digits is 1620, while the sum is 24.

The square root of 21533613 is about 4640.4324151958. The cubic root of 21533613 is about 278.2097213262.

The spelling of 21533613 in words is "twenty-one million, five hundred thirty-three thousand, six hundred thirteen".