1981951 has 4 divisors (see below), whose sum is σ = 2014504. Its totient is φ = 1949400.

The previous prime is 1981949. The next prime is 1981963. The reversal of 1981951 is 1591891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1981951 - 2¹ = 1981949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16185 + ... + 16306.

It is an arithmetic number, because the mean of its divisors is an integer number (503626).

2^1981951 is an apocalyptic number.

1981951 is a deficient number, since it is larger than the sum of its proper divisors (32553).

1981951 is an equidigital number, since it uses as much as digits as its factorization.

1981951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32552.

The product of its digits is 3240, while the sum is 34.

The square root of 1981951 is about 1407.8178149178. The cubic root of 1981951 is about 125.6119538773.

The spelling of 1981951 in words is "one million, nine hundred eighty-one thousand, nine hundred fifty-one".