20981816 has 16 divisors (see below), whose sum is σ = 40008600. Its totient is φ = 10312864.

The previous prime is 20981803. The next prime is 20981827. The reversal of 20981816 is 61818902.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21755 + ... + 22698.

Almost surely, 2^20981816 is an apocalyptic number.

It is an amenable number.

20981816 is a deficient number, since it is larger than the sum of its proper divisors (19026784).

20981816 is a wasteful number, since it uses less digits than its factorization.

20981816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44518 (or 44514 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 20981816 is about 4580.5912282150. The cubic root of 20981816 is about 275.8127624564.

The spelling of 20981816 in words is "twenty million, nine hundred eighty-one thousand, eight hundred sixteen".