261386 has 4 divisors (see below), whose sum is σ = 392082. Its totient is φ = 130692.

The previous prime is 261379. The next prime is 261389. The reversal of 261386 is 683162.

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., 185761 + 75625 = 431^2 + 275^2 .

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (261389) by changing a digit.

261386 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65345 + ... + 65348.

2²⁶¹³⁸⁶ is an apocalyptic number.

261386 is a deficient number, since it is larger than the sum of its proper divisors (130696).

261386 is a wasteful number, since it uses less digits than its factorization.

261386 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130695.

The product of its digits is 1728, while the sum is 26.

The square root of 261386 is about 511.2592297455. The cubic root of 261386 is about 63.9382542503.

The spelling of 261386 in words is "two hundred sixty-one thousand, three hundred eighty-six".