21982005 has 24 divisors (see below), whose sum is σ = 38214072. Its totient is φ = 11689344.

The previous prime is 21981991. The next prime is 21982013. The reversal of 21982005 is 50028912.

It can be written as a sum of positive squares in 4 ways, for example, as 1542564 + 20439441 = 1242^2 + 4521^2 .

It is not a de Polignac number, because 21982005 - 2⁶ = 21981941 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21982005.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24627 + ... + 25503.

It is an arithmetic number, because the mean of its divisors is an integer number (1592253).

Almost surely, 2^21982005 is an apocalyptic number.

It is an amenable number.

21982005 is a deficient number, since it is larger than the sum of its proper divisors (16232067).

21982005 is a wasteful number, since it uses less digits than its factorization.

21982005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1445 (or 1442 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 21982005 is about 4688.4970939524. The cubic root of 21982005 is about 280.1275141991.

The spelling of 21982005 in words is "twenty-one million, nine hundred eighty-two thousand, five".