21052609 has 2 divisors, whose sum is σ = 21052610. Its totient is φ = 21052608.

The previous prime is 21052597. The next prime is 21052621. The reversal of 21052609 is 90625012.

It is a balanced prime because it is at equal distance from previous prime (21052597) and next prime (21052621).

It can be written as a sum of positive squares in only one way, i.e., 16524225 + 4528384 = 4065^2 + 2128^2 .

It is a cyclic number.

It is not a de Polignac number, because 21052609 - 2⁷ = 21052481 is a prime.

It is not a weakly prime, because it can be changed into another prime (21052679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10526304 + 10526305.

It is an arithmetic number, because the mean of its divisors is an integer number (10526305).

Almost surely, 2^21052609 is an apocalyptic number.

It is an amenable number.

21052609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21052609 is an equidigital number, since it uses as much as digits as its factorization.

21052609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21052609 is about 4588.3122169268. The cubic root of 21052609 is about 276.1226132028.

It can be divided in two parts, 2105 and 2609, that multiplied together give a palindrome (5491945).

The spelling of 21052609 in words is "twenty-one million, fifty-two thousand, six hundred nine".