21478229 has 2 divisors, whose sum is σ = 21478230. Its totient is φ = 21478228.

The previous prime is 21478211. The next prime is 21478231. The reversal of 21478229 is 92287412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13126129 + 8352100 = 3623^2 + 2890^2 .

It is a cyclic number.

It is not a de Polignac number, because 21478229 - 2¹² = 21474133 is a prime.

It is a super-2 number, since 2×21478229² = 922628641952882, which contains 22 as substring.

Together with 21478231, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21478529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10739114 + 10739115.

It is an arithmetic number, because the mean of its divisors is an integer number (10739115).

Almost surely, 2^21478229 is an apocalyptic number.

It is an amenable number.

21478229 is a deficient number, since it is larger than the sum of its proper divisors (1).

21478229 is an equidigital number, since it uses as much as digits as its factorization.

21478229 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16128, while the sum is 35.

The square root of 21478229 is about 4634.4610258368. The cubic root of 21478229 is about 277.9710000286.

The spelling of 21478229 in words is "twenty-one million, four hundred seventy-eight thousand, two hundred twenty-nine".