21534320 has 20 divisors (see below), whose sum is σ = 50067480. Its totient is φ = 8613696.

The previous prime is 21534301. The next prime is 21534323. The reversal of 21534320 is 2343512.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21534292 and 21534301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21534323) 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, 134510 + ... + 134669.

It is an arithmetic number, because the mean of its divisors is an integer number (2503374).

Almost surely, 2^21534320 is an apocalyptic number.

21534320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21534320 is an abundant number, since it is smaller than the sum of its proper divisors (28533160).

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

21534320 is a wasteful number, since it uses less digits than its factorization.

21534320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269192 (or 269186 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21534320 is about 4640.5085928161. The cubic root of 21534320 is about 278.2127660563.

Adding to 21534320 its reverse (2343512), we get a palindrome (23877832).

The spelling of 21534320 in words is "twenty-one million, five hundred thirty-four thousand, three hundred twenty".