21680479 has 2 divisors, whose sum is σ = 21680480. Its totient is φ = 21680478.

The previous prime is 21680473. The next prime is 21680497. The reversal of 21680479 is 97408612.

Together with next prime (21680497) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21680479 - 2⁹ = 21679967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21680473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10840239 + 10840240.

It is an arithmetic number, because the mean of its divisors is an integer number (10840240).

Almost surely, 2^21680479 is an apocalyptic number.

21680479 is a deficient number, since it is larger than the sum of its proper divisors (1).

21680479 is an equidigital number, since it uses as much as digits as its factorization.

21680479 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21680479 is about 4656.2301274744. The cubic root of 21680479 is about 278.8407813603.

The spelling of 21680479 in words is "twenty-one million, six hundred eighty thousand, four hundred seventy-nine".