21352609 has 2 divisors, whose sum is σ = 21352610. Its totient is φ = 21352608.

The previous prime is 21352601. The next prime is 21352619. The reversal of 21352609 is 90625312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12960000 + 8392609 = 3600^2 + 2897^2 .

It is a cyclic number.

It is not a de Polignac number, because 21352609 - 2³ = 21352601 is a prime.

It is a super-2 number, since 2×21352609² = 911867822213762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21352601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10676304 + 10676305.

It is an arithmetic number, because the mean of its divisors is an integer number (10676305).

Almost surely, 2^21352609 is an apocalyptic number.

It is an amenable number.

21352609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21352609 is an equidigital number, since it uses as much as digits as its factorization.

21352609 is an evil number, because the sum of its binary digits is even.

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

The square root of 21352609 is about 4620.8883345089. Note that the first 3 decimals coincide. The cubic root of 21352609 is about 277.4280158498.

The spelling of 21352609 in words is "twenty-one million, three hundred fifty-two thousand, six hundred nine".