21185413 has 2 divisors, whose sum is σ = 21185414. Its totient is φ = 21185412.

The previous prime is 21185401. The next prime is 21185419. The reversal of 21185413 is 31458112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18472804 + 2712609 = 4298^2 + 1647^2 .

It is a cyclic number.

It is not a de Polignac number, because 21185413 - 2²¹ = 19088261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21185419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10592706 + 10592707.

It is an arithmetic number, because the mean of its divisors is an integer number (10592707).

Almost surely, 2^21185413 is an apocalyptic number.

It is an amenable number.

21185413 is a deficient number, since it is larger than the sum of its proper divisors (1).

21185413 is an equidigital number, since it uses as much as digits as its factorization.

21185413 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 25.

The square root of 21185413 is about 4602.7614537362. The cubic root of 21185413 is about 276.7020085172.

The spelling of 21185413 in words is "twenty-one million, one hundred eighty-five thousand, four hundred thirteen".