21305052 has 24 divisors (see below), whose sum is σ = 55235600. Its totient is φ = 7101648.

The previous prime is 21305047. The next prime is 21305059. The reversal of 21305052 is 25050312.

It is a happy number.

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 (21305059) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 98527 + ... + 98742.

Almost surely, 2^21305052 is an apocalyptic number.

It is an amenable number.

21305052 is an abundant number, since it is smaller than the sum of its proper divisors (33930548).

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

21305052 is a wasteful number, since it uses less digits than its factorization.

21305052 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197282 (or 197274 counting only the distinct ones).

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

The square root of 21305052 is about 4615.7395940412. The cubic root of 21305052 is about 277.2218981595.

Adding to 21305052 its reverse (25050312), we get a palindrome (46355364).

The spelling of 21305052 in words is "twenty-one million, three hundred five thousand, fifty-two".