21778982 has 4 divisors (see below), whose sum is σ = 32668476. Its totient is φ = 10889490.

The previous prime is 21778979. The next prime is 21778987. The reversal of 21778982 is 28987712.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21778987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5444744 + ... + 5444747.

It is an arithmetic number, because the mean of its divisors is an integer number (8167119).

Almost surely, 2^21778982 is an apocalyptic number.

21778982 is a deficient number, since it is larger than the sum of its proper divisors (10889494).

21778982 is a wasteful number, since it uses less digits than its factorization.

21778982 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10889493.

The product of its digits is 112896, while the sum is 44.

The square root of 21778982 is about 4666.7956886926. The cubic root of 21778982 is about 279.2624381093.

The spelling of 21778982 in words is "twenty-one million, seven hundred seventy-eight thousand, nine hundred eighty-two".