21152305 has 8 divisors (see below), whose sum is σ = 25645032. Its totient is φ = 16747008.

The previous prime is 21152291. The next prime is 21152309. The reversal of 21152305 is 50325112.

It can be written as a sum of positive squares in 4 ways, for example, as 3713329 + 17438976 = 1927^2 + 4176^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21152305 - 2¹¹ = 21150257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21152309) 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, 21322 + ... + 22291.

It is an arithmetic number, because the mean of its divisors is an integer number (3205629).

Almost surely, 2^21152305 is an apocalyptic number.

It is an amenable number.

21152305 is a deficient number, since it is larger than the sum of its proper divisors (4492727).

21152305 is an equidigital number, since it uses as much as digits as its factorization.

21152305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43715.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21152305 is about 4599.1635109007. The cubic root of 21152305 is about 276.5577925188.

Adding to 21152305 its reverse (50325112), we get a palindrome (71477417).

The spelling of 21152305 in words is "twenty-one million, one hundred fifty-two thousand, three hundred five".