21981982 has 8 divisors (see below), whose sum is σ = 35970552. Its totient is φ = 9991800.

The previous prime is 21981977. The next prime is 21981983. The reversal of 21981982 is 28918912.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21981983) 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, 499569 + ... + 499612.

It is an arithmetic number, because the mean of its divisors is an integer number (4496319).

Almost surely, 2^21981982 is an apocalyptic number.

21981982 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21981982 is a deficient number, since it is larger than the sum of its proper divisors (13988570).

21981982 is a wasteful number, since it uses less digits than its factorization.

21981982 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 999194.

The product of its digits is 20736, while the sum is 40.

The square root of 21981982 is about 4688.4946411402. The cubic root of 21981982 is about 280.1274164990.

The spelling of 21981982 in words is "twenty-one million, nine hundred eighty-one thousand, nine hundred eighty-two".