1977999840 has 72 divisors (see below), whose sum is σ = 6749929368. Its totient is φ = 527466240.

The previous prime is 1977999833. The next prime is 1977999851. The reversal of 1977999840 is 489997791.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 685366 + ... + 688245.

It is an arithmetic number, because the mean of its divisors is an integer number (93749019).

Almost surely, 2^1977999840 is an apocalyptic number.

1977999840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1977999840 is an abundant number, since it is smaller than the sum of its proper divisors (4771929528).

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

1977999840 is a wasteful number, since it uses less digits than its factorization.

1977999840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1373632 (or 1373621 counting only the distinct ones).

The product of its (nonzero) digits is 10287648, while the sum is 63.

The square root of 1977999840 is about 44474.7101170991. The cubic root of 1977999840 is about 1255.2842623124.

The spelling of 1977999840 in words is "one billion, nine hundred seventy-seven million, nine hundred ninety-nine thousand, eight hundred forty".