21428579 has 2 divisors, whose sum is σ = 21428580. Its totient is φ = 21428578.

The previous prime is 21428549. The next prime is 21428591. The reversal of 21428579 is 97582412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21428579 is a prime.

It is not a weakly prime, because it can be changed into another prime (21428509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10714289 + 10714290.

It is an arithmetic number, because the mean of its divisors is an integer number (10714290).

Almost surely, 2^21428579 is an apocalyptic number.

21428579 is a deficient number, since it is larger than the sum of its proper divisors (1).

21428579 is an equidigital number, since it uses as much as digits as its factorization.

21428579 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 38.

The square root of 21428579 is about 4629.1013166704. The cubic root of 21428579 is about 277.7566448575.

The spelling of 21428579 in words is "twenty-one million, four hundred twenty-eight thousand, five hundred seventy-nine".