1981979999 has 8 divisors (see below), whose sum is σ = 2036353728. Its totient is φ = 1927648800.

The previous prime is 1981979983. The next prime is 1981980017. The reversal of 1981979999 is 9999791891.

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

It is a cyclic number.

It is not a de Polignac number, because 1981979999 - 2⁴ = 1981979983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981979099) 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, 99149 + ... + 117449.

It is an arithmetic number, because the mean of its divisors is an integer number (254544216).

Almost surely, 2^1981979999 is an apocalyptic number.

1981979999 is a deficient number, since it is larger than the sum of its proper divisors (54373729).

1981979999 is a wasteful number, since it uses less digits than its factorization.

1981979999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21265.

The product of its digits is 29760696, while the sum is 71.

The square root of 1981979999 is about 44519.4339474347. The cubic root of 1981979999 is about 1256.1256650656.

The spelling of 1981979999 in words is "one billion, nine hundred eighty-one million, nine hundred seventy-nine thousand, nine hundred ninety-nine".