1971981 has 12 divisors (see below), whose sum is σ = 3107520. Its totient is φ = 1195080.

The previous prime is 1971967. The next prime is 1972007. The reversal of 1971981 is 1891791.

It is not a de Polignac number, because 1971981 - 2⁹ = 1971469 is a prime.

It is a super-2 number, since 2×1971981² = 7777418128722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1971901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9861 + ... + 10058.

It is an arithmetic number, because the mean of its divisors is an integer number (258960).

2^1971981 is an apocalyptic number.

1971981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1971981 is a deficient number, since it is larger than the sum of its proper divisors (1135539).

1971981 is a wasteful number, since it uses less digits than its factorization.

1971981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19936 (or 19933 counting only the distinct ones).

The product of its digits is 4536, while the sum is 36.

The square root of 1971981 is about 1404.2724094705. The cubic root of 1971981 is about 125.4009737186.

The spelling of 1971981 in words is "one million, nine hundred seventy-one thousand, nine hundred eighty-one".