261780194 has 8 divisors (see below), whose sum is σ = 422875740. Its totient is φ = 120821616.

The previous prime is 261780193. The next prime is 261780209. The reversal of 261780194 is 491087162.

It can be written as a sum of positive squares in 2 ways, for example, as 258405625 + 3374569 = 16075^2 + 1837^2 .

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

It is not an unprimeable number, because it can be changed into a prime (261780191) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5034209 + ... + 5034260.

Almost surely, 2^261780194 is an apocalyptic number.

261780194 is a deficient number, since it is larger than the sum of its proper divisors (161095546).

261780194 is a wasteful number, since it uses less digits than its factorization.

261780194 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10068484.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 261780194 is about 16179.6228015365. The cubic root of 261780194 is about 639.7037968524.

The spelling of 261780194 in words is "two hundred sixty-one million, seven hundred eighty thousand, one hundred ninety-four".