1969981 has 4 divisors (see below), whose sum is σ = 2121532. Its totient is φ = 1818432.

The previous prime is 1969969. The next prime is 1969987. The reversal of 1969981 is 1899691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1899691 = 37 ⋅51343.

It can be written as a sum of positive squares in 2 ways, for example, as 737881 + 1232100 = 859^2 + 1110^2 .

It is a cyclic number.

It is not a de Polignac number, because 1969981 - 2⁵ = 1969949 is a prime.

It is a super-2 number, since 2×1969981² = 7761650280722, which contains 22 as substring.

It is a Duffinian number.

1969981 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1969987) 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 3 ways as a sum of consecutive naturals, for example, 75756 + ... + 75781.

It is an arithmetic number, because the mean of its divisors is an integer number (530383).

2^1969981 is an apocalyptic number.

It is an amenable number.

1969981 is a deficient number, since it is larger than the sum of its proper divisors (151551).

1969981 is a wasteful number, since it uses less digits than its factorization.

1969981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151550.

The product of its digits is 34992, while the sum is 43.

The square root of 1969981 is about 1403.5601162758. The cubic root of 1969981 is about 125.3585651316.

The spelling of 1969981 in words is "one million, nine hundred sixty-nine thousand, nine hundred eighty-one".