1999778679 has 16 divisors (see below), whose sum is σ = 2968688640. Its totient is φ = 1330461720.

The previous prime is 1999778657. The next prime is 1999778707. The reversal of 1999778679 is 9768779991.

It is not a de Polignac number, because 1999778679 - 2¹⁷ = 1999647607 is a prime.

It is a super-3 number, since 3×1999778679³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1999778779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62167 + ... + 88680.

It is an arithmetic number, because the mean of its divisors is an integer number (185543040).

Almost surely, 2^1999778679 is an apocalyptic number.

1999778679 is a deficient number, since it is larger than the sum of its proper divisors (968909961).

1999778679 is a wasteful number, since it uses less digits than its factorization.

1999778679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151347 (or 151341 counting only the distinct ones).

The product of its digits is 108020304, while the sum is 72.

The square root of 1999778679 is about 44718.8850375320. The cubic root of 1999778679 is about 1259.8745736827.

The spelling of 1999778679 in words is "one billion, nine hundred ninety-nine million, seven hundred seventy-eight thousand, six hundred seventy-nine".