21982705 has 8 divisors (see below), whose sum is σ = 26405352. Its totient is φ = 17568768.

The previous prime is 21982691. The next prime is 21982721. The reversal of 21982705 is 50728912.

It can be written as a sum of positive squares in 4 ways, for example, as 3655744 + 18326961 = 1912^2 + 4281^2 .

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 21982705 - 2⁵ = 21982673 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, 6609 + ... + 9361.

It is an arithmetic number, because the mean of its divisors is an integer number (3300669).

Almost surely, 2^21982705 is an apocalyptic number.

It is an amenable number.

21982705 is a deficient number, since it is larger than the sum of its proper divisors (4422647).

21982705 is a wasteful number, since it uses less digits than its factorization.

21982705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4355.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 21982705 is about 4688.5717441455. The cubic root of 21982705 is about 280.1304876491.

The spelling of 21982705 in words is "twenty-one million, nine hundred eighty-two thousand, seven hundred five".