21351017 has 2 divisors, whose sum is σ = 21351018. Its totient is φ = 21351016.

The previous prime is 21351013. The next prime is 21351053. The reversal of 21351017 is 71015312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20894041 + 456976 = 4571^2 + 676^2 .

It is a cyclic number.

It is not a de Polignac number, because 21351017 - 2² = 21351013 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21351017.

It is not a weakly prime, because it can be changed into another prime (21351013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10675508 + 10675509.

It is an arithmetic number, because the mean of its divisors is an integer number (10675509).

Almost surely, 2^21351017 is an apocalyptic number.

It is an amenable number.

21351017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21351017 is an equidigital number, since it uses as much as digits as its factorization.

21351017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 210, while the sum is 20.

The square root of 21351017 is about 4620.7160700480. The cubic root of 21351017 is about 277.4211208863.

Adding to 21351017 its reverse (71015312), we get a palindrome (92366329).

The spelling of 21351017 in words is "twenty-one million, three hundred fifty-one thousand, seventeen".