21928579 has 2 divisors, whose sum is σ = 21928580. Its totient is φ = 21928578.

The previous prime is 21928549. The next prime is 21928601. The reversal of 21928579 is 97582912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21928579 - 2¹⁷ = 21797507 is a prime.

It is not a weakly prime, because it can be changed into another prime (21928549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10964289 + 10964290.

It is an arithmetic number, because the mean of its divisors is an integer number (10964290).

Almost surely, 2^21928579 is an apocalyptic number.

21928579 is a deficient number, since it is larger than the sum of its proper divisors (1).

21928579 is an equidigital number, since it uses as much as digits as its factorization.

21928579 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 43.

The square root of 21928579 is about 4682.7960664543. The cubic root of 21928579 is about 279.9003854831.

The spelling of 21928579 in words is "twenty-one million, nine hundred twenty-eight thousand, five hundred seventy-nine".