21020221982 has 8 divisors (see below), whose sum is σ = 33385058496. Its totient is φ = 9891869152.

The previous prime is 21020221907. The next prime is 21020221997. The reversal of 21020221982 is 28912202012.

It is a happy number.

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

It is a super-3 number, since 3×21020221982³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 309120878 + ... + 309120945.

It is an arithmetic number, because the mean of its divisors is an integer number (4173132312).

Almost surely, 2^21020221982 is an apocalyptic number.

21020221982 is a deficient number, since it is larger than the sum of its proper divisors (12364836514).

21020221982 is a wasteful number, since it uses less digits than its factorization.

21020221982 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 618241842.

The product of its (nonzero) digits is 2304, while the sum is 29.

Adding to 21020221982 its reverse (28912202012), we get a palindrome (49932423994).

The spelling of 21020221982 in words is "twenty-one billion, twenty million, two hundred twenty-one thousand, nine hundred eighty-two".