21705422 has 16 divisors (see below), whose sum is σ = 34089120. Its totient is φ = 10345632.

The previous prime is 21705419. The next prime is 21705433. The reversal of 21705422 is 22450712.

It is a happy number.

It is a super-2 number, since 2×21705422² = 942250688396168, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17288 + ... + 18500.

It is an arithmetic number, because the mean of its divisors is an integer number (2130570).

Almost surely, 2^21705422 is an apocalyptic number.

21705422 is a deficient number, since it is larger than the sum of its proper divisors (12383698).

21705422 is a wasteful number, since it uses less digits than its factorization.

21705422 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1627.

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21705422 is about 4658.9078119233. The cubic root of 21705422 is about 278.9476741411.

The spelling of 21705422 in words is "twenty-one million, seven hundred five thousand, four hundred twenty-two".