261645738 has 16 divisors (see below), whose sum is σ = 523673856. Its totient is φ = 87151520.

The previous prime is 261645667. The next prime is 261645739. The reversal of 261645738 is 837546162.

It is a self number, because there is not a number n which added to its sum of digits gives 261645738.

It is not an unprimeable number, because it can be changed into a prime (261645739) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6618 + ... + 23813.

It is an arithmetic number, because the mean of its divisors is an integer number (32729616).

Almost surely, 2^261645738 is an apocalyptic number.

261645738 is an abundant number, since it is smaller than the sum of its proper divisors (262028118).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261645738 is a wasteful number, since it uses less digits than its factorization.

261645738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31869.

The product of its digits is 241920, while the sum is 42.

The square root of 261645738 is about 16175.4671648147. The cubic root of 261645738 is about 639.5942561694.

The spelling of 261645738 in words is "two hundred sixty-one million, six hundred forty-five thousand, seven hundred thirty-eight".