21309652 has 24 divisors (see below), whose sum is σ = 45898496. Its totient is φ = 8430048.

The previous prime is 21309647. The next prime is 21309667. The reversal of 21309652 is 25690312.

It is a super-2 number, since 2×21309652² = 908202536722208, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a self number, because there is not a number n which added to its sum of digits gives 21309652.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28908 + ... + 29635.

Almost surely, 2^21309652 is an apocalyptic number.

It is an amenable number.

21309652 is an abundant number, since it is smaller than the sum of its proper divisors (24588844).

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

21309652 is a wasteful number, since it uses less digits than its factorization.

21309652 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58567 (or 58565 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 21309652 is about 4616.2378621557. The cubic root of 21309652 is about 277.2418484975.

Adding to 21309652 its reverse (25690312), we get a palindrome (46999964).

The spelling of 21309652 in words is "twenty-one million, three hundred nine thousand, six hundred fifty-two".