20809982 has 4 divisors (see below), whose sum is σ = 31214976. Its totient is φ = 10404990.

The previous prime is 20809961. The next prime is 20809991. The reversal of 20809982 is 28990802.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5202494 + ... + 5202497.

It is an arithmetic number, because the mean of its divisors is an integer number (7803744).

Almost surely, 2^20809982 is an apocalyptic number.

20809982 is a deficient number, since it is larger than the sum of its proper divisors (10404994).

20809982 is a wasteful number, since it uses less digits than its factorization.

20809982 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10404993.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 20809982 is about 4561.7959182760. The cubic root of 20809982 is about 275.0577597684.

The spelling of 20809982 in words is "twenty million, eight hundred nine thousand, nine hundred eighty-two".