19781980 has 12 divisors (see below), whose sum is σ = 41542200. Its totient is φ = 7912784.

The previous prime is 19781969. The next prime is 19781981. The reversal of 19781980 is 8918791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19781981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 494530 + ... + 494569.

It is an arithmetic number, because the mean of its divisors is an integer number (3461850).

Almost surely, 2^19781980 is an apocalyptic number.

19781980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19781980 is an abundant number, since it is smaller than the sum of its proper divisors (21760220).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19781980 is a wasteful number, since it uses less digits than its factorization.

19781980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 989108 (or 989106 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 19781980 is about 4447.6937844236. The cubic root of 19781980 is about 270.4518269238.

The spelling of 19781980 in words is "nineteen million, seven hundred eighty-one thousand, nine hundred eighty".