21827665 has 4 divisors (see below), whose sum is σ = 26193204. Its totient is φ = 17462128.

The previous prime is 21827651. The next prime is 21827683. The reversal of 21827665 is 56672812.

It is a happy number.

21827665 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7817616 + 14010049 = 2796^2 + 3743^2 .

It is a cyclic number.

It is not a de Polignac number, because 21827665 - 2⁷ = 21827537 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2182762 + ... + 2182771.

It is an arithmetic number, because the mean of its divisors is an integer number (6548301).

Almost surely, 2^21827665 is an apocalyptic number.

It is an amenable number.

21827665 is a deficient number, since it is larger than the sum of its proper divisors (4365539).

21827665 is an equidigital number, since it uses as much as digits as its factorization.

21827665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4365538.

The product of its digits is 40320, while the sum is 37.

The square root of 21827665 is about 4672.0086686563. The cubic root of 21827665 is about 279.4703635893.

The spelling of 21827665 in words is "twenty-one million, eight hundred twenty-seven thousand, six hundred sixty-five".