21417265 has 8 divisors (see below), whose sum is σ = 26395560. Its totient is φ = 16670592.

The previous prime is 21417257. The next prime is 21417269. The reversal of 21417265 is 56271412.

It can be written as a sum of positive squares in 4 ways, for example, as 13220496 + 8196769 = 3636^2 + 2863^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21417265 - 2³ = 21417257 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21417269) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57700 + ... + 58069.

It is an arithmetic number, because the mean of its divisors is an integer number (3299445).

Almost surely, 2^21417265 is an apocalyptic number.

It is an amenable number.

21417265 is a deficient number, since it is larger than the sum of its proper divisors (4978295).

21417265 is a wasteful number, since it uses less digits than its factorization.

21417265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115811.

The product of its digits is 3360, while the sum is 28.

The square root of 21417265 is about 4627.8791038660. The cubic root of 21417265 is about 277.7077523338.

Adding to 21417265 its reverse (56271412), we get a palindrome (77688677).

The spelling of 21417265 in words is "twenty-one million, four hundred seventeen thousand, two hundred sixty-five".