21785422 has 4 divisors (see below), whose sum is σ = 32678136. Its totient is φ = 10892710.

The previous prime is 21785377. The next prime is 21785437. The reversal of 21785422 is 22458712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×21785422² = 949209223436168, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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 as a sum of consecutive naturals, namely, 5446354 + ... + 5446357.

It is an arithmetic number, because the mean of its divisors is an integer number (8169534).

Almost surely, 2^21785422 is an apocalyptic number.

21785422 is a deficient number, since it is larger than the sum of its proper divisors (10892714).

21785422 is a wasteful number, since it uses less digits than its factorization.

21785422 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10892713.

The product of its digits is 8960, while the sum is 31.

The square root of 21785422 is about 4667.4856186174. The cubic root of 21785422 is about 279.2899611720.

The spelling of 21785422 in words is "twenty-one million, seven hundred eighty-five thousand, four hundred twenty-two".