21580609 has 2 divisors, whose sum is σ = 21580610. Its totient is φ = 21580608.

The previous prime is 21580597. The next prime is 21580613. The reversal of 21580609 is 90608512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18249984 + 3330625 = 4272^2 + 1825^2 .

It is a cyclic number.

It is not a de Polignac number, because 21580609 - 2⁵ = 21580577 is a prime.

It is not a weakly prime, because it can be changed into another prime (21580709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10790304 + 10790305.

It is an arithmetic number, because the mean of its divisors is an integer number (10790305).

Almost surely, 2^21580609 is an apocalyptic number.

It is an amenable number.

21580609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21580609 is an equidigital number, since it uses as much as digits as its factorization.

21580609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 21580609 is about 4645.4934075941. The cubic root of 21580609 is about 278.4119670575.

The spelling of 21580609 in words is "twenty-one million, five hundred eighty thousand, six hundred nine".