19781812 has 48 divisors (see below), whose sum is σ = 39372480. Its totient is φ = 8640000.

The previous prime is 19781789. The next prime is 19781821. The reversal of 19781812 is 21818791.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78687 + ... + 78937.

It is an arithmetic number, because the mean of its divisors is an integer number (820260).

Almost surely, 2^19781812 is an apocalyptic number.

It is an amenable number.

19781812 is a deficient number, since it is larger than the sum of its proper divisors (19590668).

19781812 is a wasteful number, since it uses less digits than its factorization.

19781812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 352 (or 350 counting only the distinct ones).

The product of its digits is 8064, while the sum is 37.

The square root of 19781812 is about 4447.6748981912. The cubic root of 19781812 is about 270.4510613106.

The spelling of 19781812 in words is "nineteen million, seven hundred eighty-one thousand, eight hundred twelve".