21534423 has 4 divisors (see below), whose sum is σ = 28712568. Its totient is φ = 14356280.

The previous prime is 21534421. The next prime is 21534437. The reversal of 21534423 is 32443512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21534423 - 2¹ = 21534421 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21534393 and 21534402.

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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3589068 + ... + 3589073.

It is an arithmetic number, because the mean of its divisors is an integer number (7178142).

Almost surely, 2^21534423 is an apocalyptic number.

21534423 is a deficient number, since it is larger than the sum of its proper divisors (7178145).

21534423 is an equidigital number, since it uses as much as digits as its factorization.

21534423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7178144.

The product of its digits is 2880, while the sum is 24.

The square root of 21534423 is about 4640.5196907243. The cubic root of 21534423 is about 278.2132096253.

Adding to 21534423 its reverse (32443512), we get a palindrome (53977935).

The spelling of 21534423 in words is "twenty-one million, five hundred thirty-four thousand, four hundred twenty-three".