21099613 has 2 divisors, whose sum is σ = 21099614. Its totient is φ = 21099612.

The previous prime is 21099593. The next prime is 21099619. The reversal of 21099613 is 31699012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16990884 + 4108729 = 4122^2 + 2027^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21099613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21099619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10549806 + 10549807.

It is an arithmetic number, because the mean of its divisors is an integer number (10549807).

Almost surely, 2^21099613 is an apocalyptic number.

It is an amenable number.

21099613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21099613 is an equidigital number, since it uses as much as digits as its factorization.

21099613 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 21099613 is about 4593.4315059659. The cubic root of 21099613 is about 276.3279594064.

It can be divided in two parts, 21099 and 613, that added together give a palindrome (21712).

The spelling of 21099613 in words is "twenty-one million, ninety-nine thousand, six hundred thirteen".