261656138 has 4 divisors (see below), whose sum is σ = 392484210. Its totient is φ = 130828068.

The previous prime is 261656123. The next prime is 261656141. The reversal of 261656138 is 831656162.

261656138 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 131171209 + 130484929 = 11453^2 + 11423^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65414033 + ... + 65414036.

Almost surely, 2^261656138 is an apocalyptic number.

261656138 is a deficient number, since it is larger than the sum of its proper divisors (130828072).

261656138 is a wasteful number, since it uses less digits than its factorization.

261656138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130828071.

The product of its digits is 51840, while the sum is 38.

The square root of 261656138 is about 16175.7886361067. The cubic root of 261656138 is about 639.6027303403.

The spelling of 261656138 in words is "two hundred sixty-one million, six hundred fifty-six thousand, one hundred thirty-eight".