21813013 has 2 divisors, whose sum is σ = 21813014. Its totient is φ = 21813012.

The previous prime is 21812983. The next prime is 21813019. The reversal of 21813013 is 31031812.

21813013 = 3302² + 3303².

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10909809 + 10903204 = 3303^2 + 3302^2 .

It is a cyclic number.

It is not a de Polignac number, because 21813013 - 2⁹ = 21812501 is a prime.

It is a super-2 number, since 2×21813013² = 951615072276338, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21813019) 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, 10906506 + 10906507.

It is an arithmetic number, because the mean of its divisors is an integer number (10906507).

Almost surely, 2^21813013 is an apocalyptic number.

21813013 is the 3303-rd centered square number.

It is an amenable number.

21813013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21813013 is an equidigital number, since it uses as much as digits as its factorization.

21813013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21813013 is about 4670.4403432653. The cubic root of 21813013 is about 279.4078173308.

Adding to 21813013 its reverse (31031812), we get a palindrome (52844825).

It can be divided in two parts, 218 and 13013, that added together give a palindrome (13231).

The spelling of 21813013 in words is "twenty-one million, eight hundred thirteen thousand, thirteen".