1999779987 has 8 divisors (see below), whose sum is σ = 2666594704. Its totient is φ = 1333075968.

The previous prime is 1999779967. The next prime is 1999780037. The reversal of 1999779987 is 7899779991.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1999779987 - 2¹⁴ = 1999763603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1999779967) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34323 + ... + 71955.

It is an arithmetic number, because the mean of its divisors is an integer number (333324338).

Almost surely, 2^1999779987 is an apocalyptic number.

1999779987 is a deficient number, since it is larger than the sum of its proper divisors (666814717).

1999779987 is a wasteful number, since it uses less digits than its factorization.

1999779987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55349.

The product of its digits is 162030456, while the sum is 75.

The square root of 1999779987 is about 44718.8996622234. The cubic root of 1999779987 is about 1259.8748483657.

The spelling of 1999779987 in words is "one billion, nine hundred ninety-nine million, seven hundred seventy-nine thousand, nine hundred eighty-seven".