19971 has 12 divisors (see below), whose sum is σ = 33072. Its totient is φ = 11376.

The previous prime is 19963. The next prime is 19973. The reversal of 19971 is 17991.

It is not a de Polignac number, because 19971 - 2³ = 19963 is a prime.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (19973) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 96 + ... + 221.

It is an arithmetic number, because the mean of its divisors is an integer number (2756).

2¹⁹⁹⁷¹ is an apocalyptic number.

19971 is a deficient number, since it is larger than the sum of its proper divisors (13101).

19971 is a wasteful number, since it uses less digits than its factorization.

19971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330 (or 327 counting only the distinct ones).

The product of its digits is 567, while the sum is 27.

The square root of 19971 is about 141.3187885598. The cubic root of 19971 is about 27.1310501345.

It can be divided in two parts, 19 and 971, that added together give a triangular number (990 = T₄₄).

The spelling of 19971 in words is "nineteen thousand, nine hundred seventy-one".