21305097 has 24 divisors (see below), whose sum is σ = 35549280. Its totient is φ = 12151680.

The previous prime is 21305071. The next prime is 21305101. The reversal of 21305097 is 79050312.

It is not a de Polignac number, because 21305097 - 2¹⁴ = 21288713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21305097.

It is not an unprimeable number, because it can be changed into a prime (21305027) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4647 + ... + 8012.

It is an arithmetic number, because the mean of its divisors is an integer number (1481220).

Almost surely, 2^21305097 is an apocalyptic number.

It is an amenable number.

21305097 is a deficient number, since it is larger than the sum of its proper divisors (14244183).

21305097 is a wasteful number, since it uses less digits than its factorization.

21305097 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12693 (or 12690 counting only the distinct ones).

The product of its (nonzero) digits is 1890, while the sum is 27.

The square root of 21305097 is about 4615.7444686637. The cubic root of 21305097 is about 277.2220933397. Note that the first 3 decimals are identical.

It can be divided in two parts, 2130 and 5097, that added together give a palindrome (7227).

The spelling of 21305097 in words is "twenty-one million, three hundred five thousand, ninety-seven".