21534403 has 16 divisors (see below), whose sum is σ = 24284160. Its totient is φ = 18928800.

The previous prime is 21534397. The next prime is 21534421. The reversal of 21534403 is 30443512.

It is not a de Polignac number, because 21534403 - 2⁹ = 21533891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21534503) 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 15 ways as a sum of consecutive naturals, for example, 44718 + ... + 45196.

It is an arithmetic number, because the mean of its divisors is an integer number (1517760).

Almost surely, 2^21534403 is an apocalyptic number.

21534403 is a deficient number, since it is larger than the sum of its proper divisors (2749757).

21534403 is a wasteful number, since it uses less digits than its factorization.

21534403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 618.

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 21534403 is about 4640.5175357927. The cubic root of 21534403 is about 278.2131234955.

Adding to 21534403 its reverse (30443512), we get a palindrome (51977915).

It can be divided in two parts, 2153 and 4403, that added together give a palindrome (6556).

The spelling of 21534403 in words is "twenty-one million, five hundred thirty-four thousand, four hundred three".