21003534 has 24 divisors (see below), whose sum is σ = 48185280. Its totient is φ = 6589248.

The previous prime is 21003527. The next prime is 21003539. The reversal of 21003534 is 43530012.

It is a super-2 number, since 2×21003534² = 882296880978312, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003539) 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 11 ways as a sum of consecutive naturals, for example, 34014 + ... + 34625.

It is an arithmetic number, because the mean of its divisors is an integer number (2007720).

Almost surely, 2^21003534 is an apocalyptic number.

21003534 is an abundant number, since it is smaller than the sum of its proper divisors (27181746).

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

21003534 is a wasteful number, since it uses less digits than its factorization.

21003534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68664 (or 68661 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21003534 is about 4582.9612697469. The cubic root of 21003534 is about 275.9078930209.

Adding to 21003534 its reverse (43530012), we get a palindrome (64533546).

The spelling of 21003534 in words is "twenty-one million, three thousand, five hundred thirty-four".