21113245 has 4 divisors (see below), whose sum is σ = 25335900. Its totient is φ = 16890592.

The previous prime is 21113243. The next prime is 21113251. The reversal of 21113245 is 54231112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5280804 + 15832441 = 2298^2 + 3979^2 .

It is a cyclic number.

It is not a de Polignac number, because 21113245 - 2¹ = 21113243 is a prime.

It is a super-2 number, since 2×21113245² = 891538228860050, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21113243) 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 in 3 ways as a sum of consecutive naturals, for example, 2111320 + ... + 2111329.

It is an arithmetic number, because the mean of its divisors is an integer number (6333975).

Almost surely, 2^21113245 is an apocalyptic number.

It is an amenable number.

21113245 is a deficient number, since it is larger than the sum of its proper divisors (4222655).

21113245 is an equidigital number, since it uses as much as digits as its factorization.

21113245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4222654.

The product of its digits is 240, while the sum is 19.

The square root of 21113245 is about 4594.9151243521. The cubic root of 21113245 is about 276.3874564186.

Adding to 21113245 its reverse (54231112), we get a palindrome (75344357).

It can be divided in two parts, 2111 and 3245, that added together give a triangular number (5356 = T₁₀₃).

The spelling of 21113245 in words is "twenty-one million, one hundred thirteen thousand, two hundred forty-five".