21677605 has 8 divisors (see below), whose sum is σ = 26103672. Its totient is φ = 17281728.

The previous prime is 21677599. The next prime is 21677609. The reversal of 21677605 is 50677612.

It can be written as a sum of positive squares in 4 ways, for example, as 5541316 + 16136289 = 2354^2 + 4017^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21677605 - 2⁵ = 21677573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21677609) 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 7 ways as a sum of consecutive naturals, for example, 5934 + ... + 8863.

It is an arithmetic number, because the mean of its divisors is an integer number (3262959).

Almost surely, 2^21677605 is an apocalyptic number.

It is an amenable number.

21677605 is a deficient number, since it is larger than the sum of its proper divisors (4426067).

21677605 is a wasteful number, since it uses less digits than its factorization.

21677605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15095.

The product of its (nonzero) digits is 17640, while the sum is 34.

The square root of 21677605 is about 4655.9214984791. The cubic root of 21677605 is about 278.8284596181.

The spelling of 21677605 in words is "twenty-one million, six hundred seventy-seven thousand, six hundred five".