21432665 has 32 divisors (see below), whose sum is σ = 29963520. Its totient is φ = 14598144.

The previous prime is 21432661. The next prime is 21432673. The reversal of 21432665 is 56623412.

It is a cyclic number.

It is not a de Polignac number, because 21432665 - 2² = 21432661 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21432661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 36857 + ... + 37433.

It is an arithmetic number, because the mean of its divisors is an integer number (936360).

Almost surely, 2^21432665 is an apocalyptic number.

It is an amenable number.

21432665 is a deficient number, since it is larger than the sum of its proper divisors (8530855).

21432665 is a wasteful number, since it uses less digits than its factorization.

21432665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 641.

The product of its digits is 8640, while the sum is 29.

The square root of 21432665 is about 4629.5426339974. The cubic root of 21432665 is about 277.7742979416.

The spelling of 21432665 in words is "twenty-one million, four hundred thirty-two thousand, six hundred sixty-five".