261663994 has 8 divisors (see below), whose sum is σ = 405157248. Its totient is φ = 126611580.

The previous prime is 261663977. The next prime is 261664003. The reversal of 261663994 is 499366162.

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

It is an unprimeable number.

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, 2110132 + ... + 2110255.

It is an arithmetic number, because the mean of its divisors is an integer number (50644656).

Almost surely, 2^261663994 is an apocalyptic number.

261663994 is a deficient number, since it is larger than the sum of its proper divisors (143493254).

261663994 is a wasteful number, since it uses less digits than its factorization.

261663994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4220420.

The product of its digits is 419904, while the sum is 46.

The square root of 261663994 is about 16176.0314663393. The cubic root of 261663994 is about 639.6091314498.

The spelling of 261663994 in words is "two hundred sixty-one million, six hundred sixty-three thousand, nine hundred ninety-four".