21533430 has 32 divisors (see below), whose sum is σ = 51819264. Its totient is φ = 5726816.

The previous prime is 21533363. The next prime is 21533431. The reversal of 21533430 is 3433512.

It is a junction number, because it is equal to n+sod(n) for n = 21533397 and 21533406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533431) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14377 + ... + 15803.

It is an arithmetic number, because the mean of its divisors is an integer number (1619352).

Almost surely, 2^21533430 is an apocalyptic number.

21533430 is an abundant number, since it is smaller than the sum of its proper divisors (30285834).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21533430 is a wasteful number, since it uses less digits than its factorization.

21533430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1940.

The product of its (nonzero) digits is 1080, while the sum is 21.

The square root of 21533430 is about 4640.4126971639. The cubic root of 21533430 is about 278.2089332169.

Adding to 21533430 its reverse (3433512), we get a palindrome (24966942).

The spelling of 21533430 in words is "twenty-one million, five hundred thirty-three thousand, four hundred thirty".