21000313 has 2 divisors, whose sum is σ = 21000314. Its totient is φ = 21000312.

The previous prime is 21000307. The next prime is 21000337. The reversal of 21000313 is 31300012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13860729 + 7139584 = 3723^2 + 2672^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21000313 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21000313.

It is not a weakly prime, because it can be changed into another prime (21000613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500156 + 10500157.

It is an arithmetic number, because the mean of its divisors is an integer number (10500157).

Almost surely, 2^21000313 is an apocalyptic number.

It is an amenable number.

21000313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000313 is an equidigital number, since it uses as much as digits as its factorization.

21000313 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18, while the sum is 10.

The square root of 21000313 is about 4582.6098459284. The cubic root of 21000313 is about 275.8937883349.

Adding to 21000313 its reverse (31300012), we get a palindrome (52300325).

The spelling of 21000313 in words is "twenty-one million, three hundred thirteen", and thus it is an aban number.