21428489 has 2 divisors, whose sum is σ = 21428490. Its totient is φ = 21428488.

The previous prime is 21428461. The next prime is 21428497. The reversal of 21428489 is 98482412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11868025 + 9560464 = 3445^2 + 3092^2 .

It is a cyclic number.

It is not a de Polignac number, because 21428489 - 2¹⁶ = 21362953 is a prime.

It is not a weakly prime, because it can be changed into another prime (21428089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10714244 + 10714245.

It is an arithmetic number, because the mean of its divisors is an integer number (10714245).

Almost surely, 2^21428489 is an apocalyptic number.

It is an amenable number.

21428489 is a deficient number, since it is larger than the sum of its proper divisors (1).

21428489 is an equidigital number, since it uses as much as digits as its factorization.

21428489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36864, while the sum is 38.

The square root of 21428489 is about 4629.0915955509. The cubic root of 21428489 is about 277.7562559978.

The spelling of 21428489 in words is "twenty-one million, four hundred twenty-eight thousand, four hundred eighty-nine".