19971243 has 12 divisors (see below), whose sum is σ = 30544488. Its totient is φ = 12530880.

The previous prime is 19971239. The next prime is 19971251. The reversal of 19971243 is 34217991.

It is not a de Polignac number, because 19971243 - 2² = 19971239 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 19971198 and 19971207.

It is not an unprimeable number, because it can be changed into a prime (19971253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 65113 + ... + 65418.

It is an arithmetic number, because the mean of its divisors is an integer number (2545374).

Almost surely, 2^19971243 is an apocalyptic number.

19971243 is a deficient number, since it is larger than the sum of its proper divisors (10573245).

19971243 is a wasteful number, since it uses less digits than its factorization.

19971243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130554 (or 130551 counting only the distinct ones).

The product of its digits is 13608, while the sum is 36.

The square root of 19971243 is about 4468.9196681077. The cubic root of 19971243 is about 271.3116017437.

It can be divided in two parts, 1997 and 1243, that added together give a triangular number (3240 = T₈₀).

The spelling of 19971243 in words is "nineteen million, nine hundred seventy-one thousand, two hundred forty-three".