21306452 has 12 divisors (see below), whose sum is σ = 37447956. Its totient is φ = 10607040.

The previous prime is 21306433. The next prime is 21306473. The reversal of 21306452 is 25460312.

It can be written as a sum of positive squares in 2 ways, for example, as 12931216 + 8375236 = 3596^2 + 2894^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10499 + ... + 12362.

It is an arithmetic number, because the mean of its divisors is an integer number (3120663).

Almost surely, 2^21306452 is an apocalyptic number.

It is an amenable number.

21306452 is a deficient number, since it is larger than the sum of its proper divisors (16141504).

21306452 is a wasteful number, since it uses less digits than its factorization.

21306452 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23098 (or 23096 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21306452 is about 4615.8912465525. The cubic root of 21306452 is about 277.2279703054.

Adding to 21306452 its reverse (25460312), we get a palindrome (46766764).

The spelling of 21306452 in words is "twenty-one million, three hundred six thousand, four hundred fifty-two".