1978781805 has 192 divisors, whose sum is σ = 4778661888. Its totient is φ = 758626560.

The previous prime is 1978781797. The next prime is 1978781837. The reversal of 1978781805 is 5081878791.

It is not a de Polignac number, because 1978781805 - 2³ = 1978781797 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1215402 + ... + 1217028.

It is an arithmetic number, because the mean of its divisors is an integer number (24888864).

Almost surely, 2^1978781805 is an apocalyptic number.

1978781805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1978781805 is an abundant number, since it is smaller than the sum of its proper divisors (2799880083).

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

1978781805 is a wasteful number, since it uses less digits than its factorization.

1978781805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1678 (or 1666 counting only the distinct ones).

The product of its (nonzero) digits is 1128960, while the sum is 54.

The square root of 1978781805 is about 44483.5003681140. The cubic root of 1978781805 is about 1255.4496581862.

The spelling of 1978781805 in words is "one billion, nine hundred seventy-eight million, seven hundred eighty-one thousand, eight hundred five".