21304477 has 2 divisors, whose sum is σ = 21304478. Its totient is φ = 21304476.

The previous prime is 21304469. The next prime is 21304499. The reversal of 21304477 is 77440312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10929636 + 10374841 = 3306^2 + 3221^2 .

It is a cyclic number.

It is not a de Polignac number, because 21304477 - 2³ = 21304469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21304427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10652238 + 10652239.

It is an arithmetic number, because the mean of its divisors is an integer number (10652239).

Almost surely, 2^21304477 is an apocalyptic number.

It is an amenable number.

21304477 is a deficient number, since it is larger than the sum of its proper divisors (1).

21304477 is an equidigital number, since it uses as much as digits as its factorization.

21304477 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4704, while the sum is 28.

The square root of 21304477 is about 4615.6773067449. The cubic root of 21304477 is about 277.2194041653.

Adding to 21304477 its reverse (77440312), we get a palindrome (98744789).

The spelling of 21304477 in words is "twenty-one million, three hundred four thousand, four hundred seventy-seven".