21705746 has 16 divisors (see below), whose sum is σ = 34257600. Its totient is φ = 10299408.

The previous prime is 21705743. The next prime is 21705773. The reversal of 21705746 is 64750712.

It is a super-2 number, since 2×21705746² = 942278818833032, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21705743) 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, 251 + ... + 6593.

It is an arithmetic number, because the mean of its divisors is an integer number (2141100).

Almost surely, 2^21705746 is an apocalyptic number.

21705746 is a deficient number, since it is larger than the sum of its proper divisors (12551854).

21705746 is a wasteful number, since it uses less digits than its factorization.

21705746 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6433.

The product of its (nonzero) digits is 11760, while the sum is 32.

The square root of 21705746 is about 4658.9425838918. The cubic root of 21705746 is about 278.9490620984.

The spelling of 21705746 in words is "twenty-one million, seven hundred five thousand, seven hundred forty-six".