261658605 has 16 divisors (see below), whose sum is σ = 450858240. Its totient is φ = 128816448.

The previous prime is 261658591. The next prime is 261658609. The reversal of 261658605 is 506856162.

It is not a de Polignac number, because 261658605 - 2⁹ = 261658093 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261658609) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 670725 + ... + 671114.

It is an arithmetic number, because the mean of its divisors is an integer number (28178640).

Almost surely, 2^261658605 is an apocalyptic number.

It is an amenable number.

261658605 is a deficient number, since it is larger than the sum of its proper divisors (189199635).

261658605 is a wasteful number, since it uses less digits than its factorization.

261658605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1341860.

The product of its (nonzero) digits is 86400, while the sum is 39.

The square root of 261658605 is about 16175.8648918690. The cubic root of 261658605 is about 639.6047404785.

The spelling of 261658605 in words is "two hundred sixty-one million, six hundred fifty-eight thousand, six hundred five".