21490279 has 2 divisors, whose sum is σ = 21490280. Its totient is φ = 21490278.

The previous prime is 21490243. The next prime is 21490283. The reversal of 21490279 is 97209412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21490279 - 2⁷ = 21490151 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21490879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10745139 + 10745140.

It is an arithmetic number, because the mean of its divisors is an integer number (10745140).

Almost surely, 2^21490279 is an apocalyptic number.

21490279 is a deficient number, since it is larger than the sum of its proper divisors (1).

21490279 is an equidigital number, since it uses as much as digits as its factorization.

21490279 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21490279 is about 4635.7608868448. The cubic root of 21490279 is about 278.0229739653.

The spelling of 21490279 in words is "twenty-one million, four hundred ninety thousand, two hundred seventy-nine".