21812353 has 2 divisors, whose sum is σ = 21812354. Its totient is φ = 21812352.

The previous prime is 21812279. The next prime is 21812381. The reversal of 21812353 is 35321812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19642624 + 2169729 = 4432^2 + 1473^2 .

It is a cyclic number.

It is not a de Polignac number, because 21812353 - 2¹⁷ = 21681281 is a prime.

It is equal to p_1378105 and since 21812353 and 1378105 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21812383) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10906176 + 10906177.

It is an arithmetic number, because the mean of its divisors is an integer number (10906177).

Almost surely, 2^21812353 is an apocalyptic number.

It is an amenable number.

21812353 is a deficient number, since it is larger than the sum of its proper divisors (1).

21812353 is an equidigital number, since it uses as much as digits as its factorization.

21812353 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1440, while the sum is 25.

The square root of 21812353 is about 4670.3696855816. The cubic root of 21812353 is about 279.4049992726.

The spelling of 21812353 in words is "twenty-one million, eight hundred twelve thousand, three hundred fifty-three".