21503052 has 18 divisors (see below), whose sum is σ = 54355028. Its totient is φ = 7167672.

The previous prime is 21503051. The next prime is 21503063. The reversal of 21503052 is 25030512.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (18).

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

It is not an unprimeable number, because it can be changed into a prime (21503051) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 298618 + ... + 298689.

Almost surely, 2^21503052 is an apocalyptic number.

It is an amenable number.

21503052 is an abundant number, since it is smaller than the sum of its proper divisors (32851976).

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

21503052 is a wasteful number, since it uses less digits than its factorization.

21503052 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 597317 (or 597312 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 21503052 is about 4637.1383416931. The cubic root of 21503052 is about 278.0780451305.

Adding to 21503052 its reverse (25030512), we get a palindrome (46533564).

The spelling of 21503052 in words is "twenty-one million, five hundred three thousand, fifty-two".