19991012 has 6 divisors (see below), whose sum is σ = 34984278. Its totient is φ = 9995504.

The previous prime is 19991011. The next prime is 19991039. The reversal of 19991012 is 21019991.

It can be written as a sum of positive squares in only one way, i.e., 12559936 + 7431076 = 3544^2 + 2726^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 19991012.

It is not an unprimeable number, because it can be changed into a prime (19991011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2498873 + ... + 2498880.

It is an arithmetic number, because the mean of its divisors is an integer number (5830713).

Almost surely, 2^19991012 is an apocalyptic number.

It is an amenable number.

19991012 is a deficient number, since it is larger than the sum of its proper divisors (14993266).

19991012 is a wasteful number, since it uses less digits than its factorization.

19991012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4997757 (or 4997755 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 32.

The square root of 19991012 is about 4471.1309531258. The cubic root of 19991012 is about 271.4010935909.

The spelling of 19991012 in words is "nineteen million, nine hundred ninety-one thousand, twelve".