21296665 has 16 divisors (see below), whose sum is σ = 29142288. Its totient is φ = 14800896.

The previous prime is 21296651. The next prime is 21296669. The reversal of 21296665 is 56669212.

It can be written as a sum of positive squares in 8 ways, for example, as 35344 + 21261321 = 188^2 + 4611^2 .

It is a cyclic number.

It is not a de Polignac number, because 21296665 - 2⁵ = 21296633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21296669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8532 + ... + 10741.

It is an arithmetic number, because the mean of its divisors is an integer number (1821393).

Almost surely, 2^21296665 is an apocalyptic number.

It is an amenable number.

21296665 is a deficient number, since it is larger than the sum of its proper divisors (7845623).

21296665 is a wasteful number, since it uses less digits than its factorization.

21296665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19308.

The product of its digits is 38880, while the sum is 37.

The square root of 21296665 is about 4614.8309828205. The cubic root of 21296665 is about 277.1855160966.

The spelling of 21296665 in words is "twenty-one million, two hundred ninety-six thousand, six hundred sixty-five".