21253365 has 48 divisors (see below), whose sum is σ = 42556800. Its totient is φ = 9611136.

The previous prime is 21253363. The next prime is 21253367. The reversal of 21253365 is 56335212.

It is an interprime number because it is at equal distance from previous prime (21253363) and next prime (21253367).

It is not a de Polignac number, because 21253365 - 2¹ = 21253363 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253361) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 34026 + ... + 34644.

It is an arithmetic number, because the mean of its divisors is an integer number (886600).

Almost surely, 2^21253365 is an apocalyptic number.

It is an amenable number.

21253365 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

21253365 is a wasteful number, since it uses less digits than its factorization.

21253365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 746 (or 743 counting only the distinct ones).

The product of its digits is 5400, while the sum is 27.

The square root of 21253365 is about 4610.1371996937. The cubic root of 21253365 is about 276.9975324190.

Adding to 21253365 its reverse (56335212), we get a palindrome (77588577).

The spelling of 21253365 in words is "twenty-one million, two hundred fifty-three thousand, three hundred sixty-five".