21534420 has 24 divisors (see below), whose sum is σ = 60296544. Its totient is φ = 5742496.

The previous prime is 21534397. The next prime is 21534421. The reversal of 21534420 is 2443512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21534421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 179394 + ... + 179513.

It is an arithmetic number, because the mean of its divisors is an integer number (2512356).

Almost surely, 2^21534420 is an apocalyptic number.

21534420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21534420 is an abundant number, since it is smaller than the sum of its proper divisors (38762124).

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

21534420 is a wasteful number, since it uses less digits than its factorization.

21534420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358919 (or 358917 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21534420 is about 4640.5193674846. The cubic root of 21534420 is about 278.2131967059.

Adding to 21534420 its reverse (2443512), we get a palindrome (23977932).

The spelling of 21534420 in words is "twenty-one million, five hundred thirty-four thousand, four hundred twenty".