21705677 has 6 divisors (see below), whose sum is σ = 25249518. Its totient is φ = 18604824.

The previous prime is 21705667. The next prime is 21705679. The reversal of 21705677 is 77650712.

It can be written as a sum of positive squares in only one way, i.e., 12348196 + 9357481 = 3514^2 + 3059^2 .

It is not a de Polignac number, because 21705677 - 2⁴ = 21705661 is a prime.

It is a super-2 number, since 2×21705677² = 942272828056658, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21705679) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 221438 + ... + 221535.

It is an arithmetic number, because the mean of its divisors is an integer number (4208253).

Almost surely, 2^21705677 is an apocalyptic number.

It is an amenable number.

21705677 is a deficient number, since it is larger than the sum of its proper divisors (3543841).

21705677 is an equidigital number, since it uses as much as digits as its factorization.

21705677 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442987 (or 442980 counting only the distinct ones).

The product of its (nonzero) digits is 20580, while the sum is 35.

The square root of 21705677 is about 4658.9351787721. The cubic root of 21705677 is about 278.9487665160.

The spelling of 21705677 in words is "twenty-one million, seven hundred five thousand, six hundred seventy-seven".