21393265 has 8 divisors (see below), whose sum is σ = 25714728. Its totient is φ = 17086080.

The previous prime is 21393263. The next prime is 21393269. The reversal of 21393265 is 56239312.

It can be written as a sum of positive squares in 4 ways, for example, as 1962801 + 19430464 = 1401^2 + 4408^2 .

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

It is not a de Polignac number, because 21393265 - 2¹ = 21393263 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21393263) 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, 69 + ... + 6541.

It is an arithmetic number, because the mean of its divisors is an integer number (3214341).

Almost surely, 2^21393265 is an apocalyptic number.

It is an amenable number.

21393265 is a deficient number, since it is larger than the sum of its proper divisors (4321463).

21393265 is an equidigital number, since it uses as much as digits as its factorization.

21393265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7139.

The product of its digits is 9720, while the sum is 31.

The square root of 21393265 is about 4625.2853965999. The cubic root of 21393265 is about 277.6039812690.

The spelling of 21393265 in words is "twenty-one million, three hundred ninety-three thousand, two hundred sixty-five".