21403313 has 2 divisors, whose sum is σ = 21403314. Its totient is φ = 21403312.

The previous prime is 21403303. The next prime is 21403337. The reversal of 21403313 is 31330412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21003889 + 399424 = 4583^2 + 632^2 .

It is a cyclic number.

It is not a de Polignac number, because 21403313 - 2¹⁰ = 21402289 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21403291 and 21403300.

It is not a weakly prime, because it can be changed into another prime (21403303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701656 + 10701657.

It is an arithmetic number, because the mean of its divisors is an integer number (10701657).

Almost surely, 2^21403313 is an apocalyptic number.

It is an amenable number.

21403313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21403313 is an equidigital number, since it uses as much as digits as its factorization.

21403313 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 17.

The square root of 21403313 is about 4626.3714723312. The cubic root of 21403313 is about 277.6474361946.

Adding to 21403313 its reverse (31330412), we get a palindrome (52733725).

The spelling of 21403313 in words is "twenty-one million, four hundred three thousand, three hundred thirteen".