197661865 has 4 divisors (see below), whose sum is σ = 237194244. Its totient is φ = 158129488.

The previous prime is 197661853. The next prime is 197661917. The reversal of 197661865 is 568166791.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 568166791 = 31 ⋅18327961.

It can be written as a sum of positive squares in 2 ways, for example, as 116877721 + 80784144 = 10811^2 + 8988^2 .

It is a cyclic number.

It is not a de Polignac number, because 197661865 - 2⁵ = 197661833 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19766182 + ... + 19766191.

It is an arithmetic number, because the mean of its divisors is an integer number (59298561).

Almost surely, 2^197661865 is an apocalyptic number.

It is an amenable number.

197661865 is a deficient number, since it is larger than the sum of its proper divisors (39532379).

197661865 is an equidigital number, since it uses as much as digits as its factorization.

197661865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39532378.

The product of its digits is 544320, while the sum is 49.

The square root of 197661865 is about 14059.2270413419. The cubic root of 197661865 is about 582.5156927502.

The spelling of 197661865 in words is "one hundred ninety-seven million, six hundred sixty-one thousand, eight hundred sixty-five".