21375245 has 4 divisors (see below), whose sum is σ = 25650300. Its totient is φ = 17100192.

The previous prime is 21375241. The next prime is 21375253. The reversal of 21375245 is 54257312.

It is a happy number.

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 3108169 + 18267076 = 1763^2 + 4274^2 .

It is a cyclic number.

It is not a de Polignac number, because 21375245 - 2² = 21375241 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21375241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2137520 + ... + 2137529.

It is an arithmetic number, because the mean of its divisors is an integer number (6412575).

Almost surely, 2^21375245 is an apocalyptic number.

It is an amenable number.

21375245 is a deficient number, since it is larger than the sum of its proper divisors (4275055).

21375245 is an equidigital number, since it uses as much as digits as its factorization.

21375245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4275054.

The product of its digits is 8400, while the sum is 29.

The square root of 21375245 is about 4623.3369983163. The cubic root of 21375245 is about 277.5260154708.

The spelling of 21375245 in words is "twenty-one million, three hundred seventy-five thousand, two hundred forty-five".