21435665 has 8 divisors (see below), whose sum is σ = 25784808. Its totient is φ = 17107200.

The previous prime is 21435643. The next prime is 21435677. The reversal of 21435665 is 56653412.

It can be written as a sum of positive squares in 4 ways, for example, as 3125824 + 18309841 = 1768^2 + 4279^2 .

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

It is not a de Polignac number, because 21435665 - 2⁸ = 21435409 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2786 + ... + 7115.

It is an arithmetic number, because the mean of its divisors is an integer number (3223101).

Almost surely, 2^21435665 is an apocalyptic number.

It is an amenable number.

21435665 is a deficient number, since it is larger than the sum of its proper divisors (4349143).

21435665 is an equidigital number, since it uses as much as digits as its factorization.

21435665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10339.

The product of its digits is 21600, while the sum is 32.

The square root of 21435665 is about 4629.8666287486. The cubic root of 21435665 is about 277.7872576617.

The spelling of 21435665 in words is "twenty-one million, four hundred thirty-five thousand, six hundred sixty-five".