21013117 has 2 divisors, whose sum is σ = 21013118. Its totient is φ = 21013116.

The previous prime is 21013103. The next prime is 21013127. The reversal of 21013117 is 71131012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20985561 + 27556 = 4581^2 + 166^2 .

It is a cyclic number.

It is not a de Polignac number, because 21013117 - 2²³ = 12624509 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21013117.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21013127) 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, 10506558 + 10506559.

It is an arithmetic number, because the mean of its divisors is an integer number (10506559).

Almost surely, 2^21013117 is an apocalyptic number.

It is an amenable number.

21013117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21013117 is an equidigital number, since it uses as much as digits as its factorization.

21013117 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 42, while the sum is 16.

The square root of 21013117 is about 4584.0066535728. The cubic root of 21013117 is about 275.9498482354.

Adding to 21013117 its reverse (71131012), we get a palindrome (92144129).

The spelling of 21013117 in words is "twenty-one million, thirteen thousand, one hundred seventeen".