195643981 has 8 divisors (see below), whose sum is σ = 210976920. Its totient is φ = 180351552.

The previous prime is 195643963. The next prime is 195643997. The reversal of 195643981 is 189346591.

195643981 = 9890² + 9891².

195643981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 3572100 + 192071881 = 1890^2 + 13859^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 195643981 - 2⁵ = 195643949 is a prime.

It is a super-2 number, since 2×195643981² = 76553134603056722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (195643961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 315 + ... + 19783.

It is an arithmetic number, because the mean of its divisors is an integer number (26372115).

Almost surely, 2^195643981 is an apocalyptic number.

195643981 is the 9891-st centered square number.

It is an amenable number.

195643981 is a deficient number, since it is larger than the sum of its proper divisors (15332939).

195643981 is a wasteful number, since it uses less digits than its factorization.

195643981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20255.

The product of its digits is 233280, while the sum is 46.

The square root of 195643981 is about 13987.2792565245. The cubic root of 195643981 is about 580.5266530337.

The spelling of 195643981 in words is "one hundred ninety-five million, six hundred forty-three thousand, nine hundred eighty-one".