21624665 has 8 divisors (see below), whose sum is σ = 26013768. Its totient is φ = 17256960.

The previous prime is 21624661. The next prime is 21624667. The reversal of 21624665 is 56642612.

It can be written as a sum of positive squares in 4 ways, for example, as 712336 + 20912329 = 844^2 + 4573^2 .

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

It is not a de Polignac number, because 21624665 - 2² = 21624661 is a prime.

It is a super-2 number, since 2×21624665² = 935252272724450, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21624661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3032 + ... + 7241.

It is an arithmetic number, because the mean of its divisors is an integer number (3251721).

Almost surely, 2^21624665 is an apocalyptic number.

It is an amenable number.

21624665 is a deficient number, since it is larger than the sum of its proper divisors (4389103).

21624665 is a wasteful number, since it uses less digits than its factorization.

21624665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10699.

The product of its digits is 17280, while the sum is 32.

The square root of 21624665 is about 4650.2327898719. The cubic root of 21624665 is about 278.6012941275.

The spelling of 21624665 in words is "twenty-one million, six hundred twenty-four thousand, six hundred sixty-five".