21280579 has 2 divisors, whose sum is σ = 21280580. Its totient is φ = 21280578.

The previous prime is 21280573. The next prime is 21280639. The reversal of 21280579 is 97508212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21280579 - 2⁵ = 21280547 is a prime.

It is not a weakly prime, because it can be changed into another prime (21280573) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10640289 + 10640290.

It is an arithmetic number, because the mean of its divisors is an integer number (10640290).

Almost surely, 2^21280579 is an apocalyptic number.

21280579 is a deficient number, since it is larger than the sum of its proper divisors (1).

21280579 is an equidigital number, since it uses as much as digits as its factorization.

21280579 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 21280579 is about 4613.0877945255. The cubic root of 21280579 is about 277.1157097161.

The spelling of 21280579 in words is "twenty-one million, two hundred eighty thousand, five hundred seventy-nine".