20509982 has 4 divisors (see below), whose sum is σ = 30764976. Its totient is φ = 10254990.

The previous prime is 20509981. The next prime is 20510027. The reversal of 20509982 is 28990502.

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 (20509981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5127494 + ... + 5127497.

It is an arithmetic number, because the mean of its divisors is an integer number (7691244).

Almost surely, 2^20509982 is an apocalyptic number.

20509982 is a deficient number, since it is larger than the sum of its proper divisors (10254994).

20509982 is a wasteful number, since it uses less digits than its factorization.

20509982 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10254993.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 20509982 is about 4528.7947624064. The cubic root of 20509982 is about 273.7295980848.

The spelling of 20509982 in words is "twenty million, five hundred nine thousand, nine hundred eighty-two".