261686542 has 32 divisors (see below), whose sum is σ = 450201024. Its totient is φ = 113011200.

The previous prime is 261686527. The next prime is 261686549. The reversal of 261686542 is 245686162.

It is a junction number, because it is equal to n+sod(n) for n = 261686495 and 261686504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261686549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78367 + ... + 81637.

It is an arithmetic number, because the mean of its divisors is an integer number (14068782).

Almost surely, 2^261686542 is an apocalyptic number.

261686542 is a deficient number, since it is larger than the sum of its proper divisors (188514482).

261686542 is a wasteful number, since it uses less digits than its factorization.

261686542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3484.

The product of its digits is 138240, while the sum is 40.

The square root of 261686542 is about 16176.7284084267. The cubic root of 261686542 is about 639.6275029654.

It can be divided in two parts, 26168 and 6542, that multiplied together give a square (171191056 = 13084²).

The spelling of 261686542 in words is "two hundred sixty-one million, six hundred eighty-six thousand, five hundred forty-two".