1999521979 has 36 divisors (see below), whose sum is σ = 2600239680. Its totient is φ = 1530809280.

The previous prime is 1999521967. The next prime is 1999522027. The reversal of 1999521979 is 9791259991.

It is not a de Polignac number, because 1999521979 - 2¹³ = 1999513787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1999521949) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 252817 + ... + 260605.

It is an arithmetic number, because the mean of its divisors is an integer number (72228880).

Almost surely, 2^1999521979 is an apocalyptic number.

1999521979 is a deficient number, since it is larger than the sum of its proper divisors (600717701).

1999521979 is a wasteful number, since it uses less digits than its factorization.

1999521979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7860 (or 7840 counting only the distinct ones).

The product of its digits is 4133430, while the sum is 61.

The square root of 1999521979 is about 44716.0147933601. The cubic root of 1999521979 is about 1259.8206637766.

The spelling of 1999521979 in words is "one billion, nine hundred ninety-nine million, five hundred twenty-one thousand, nine hundred seventy-nine".