19999971 has 6 divisors (see below), whose sum is σ = 28888860. Its totient is φ = 13333308.

The previous prime is 19999963. The next prime is 19999981. The reversal of 19999971 is 17999991.

It is not a de Polignac number, because 19999971 - 2³ = 19999963 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19999981) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1111101 + ... + 1111118.

It is an arithmetic number, because the mean of its divisors is an integer number (4814810).

Almost surely, 2^19999971 is an apocalyptic number.

19999971 is a deficient number, since it is larger than the sum of its proper divisors (8888889).

19999971 is a wasteful number, since it uses less digits than its factorization.

19999971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2222225 (or 2222222 counting only the distinct ones).

The product of its digits is 413343, while the sum is 54.

The square root of 19999971 is about 4472.1327126998. The cubic root of 19999971 is about 271.4416304626.

The spelling of 19999971 in words is "nineteen million, nine hundred ninety-nine thousand, nine hundred seventy-one".