21820782 has 8 divisors (see below), whose sum is σ = 43641576. Its totient is φ = 7273592.

The previous prime is 21820781. The next prime is 21820793. The reversal of 21820782 is 28702812.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

21820782 is an admirable number.

It is a super-2 number, since 2×21820782² = 952293054183048, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1818393 + ... + 1818404.

It is an arithmetic number, because the mean of its divisors is an integer number (5455197).

Almost surely, 2^21820782 is an apocalyptic number.

21820782 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21820782 is a wasteful number, since it uses less digits than its factorization.

21820782 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3636802.

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 21820782 is about 4671.2719895121. The cubic root of 21820782 is about 279.4409850195.

The spelling of 21820782 in words is "twenty-one million, eight hundred twenty thousand, seven hundred eighty-two".