1981999612 has 12 divisors (see below), whose sum is σ = 3469573800. Its totient is φ = 990692816.

The previous prime is 1981999583. The next prime is 1981999619. The reversal of 1981999612 is 2169991891.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981999619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61903 + ... + 88294.

It is an arithmetic number, because the mean of its divisors is an integer number (289131150).

Almost surely, 2^1981999612 is an apocalyptic number.

It is an amenable number.

1981999612 is a deficient number, since it is larger than the sum of its proper divisors (1487574188).

1981999612 is a wasteful number, since it uses less digits than its factorization.

1981999612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153500 (or 153498 counting only the distinct ones).

The product of its digits is 629856, while the sum is 55.

The square root of 1981999612 is about 44519.6542214784. The cubic root of 1981999612 is about 1256.1298084494.

The spelling of 1981999612 in words is "one billion, nine hundred eighty-one million, nine hundred ninety-nine thousand, six hundred twelve".