261587634 has 64 divisors (see below), whose sum is σ = 654013440. Its totient is φ = 67763520.

The previous prime is 261587633. The next prime is 261587659. The reversal of 261587634 is 436785162.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261587633) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 315132 + ... + 315960.

It is an arithmetic number, because the mean of its divisors is an integer number (10218960).

Almost surely, 2^261587634 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261587634, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (327006720).

261587634 is an abundant number, since it is smaller than the sum of its proper divisors (392425806).

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

261587634 is a wasteful number, since it uses less digits than its factorization.

261587634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1535.

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

The square root of 261587634 is about 16173.6710118637. The cubic root of 261587634 is about 639.5469074958.

The spelling of 261587634 in words is "two hundred sixty-one million, five hundred eighty-seven thousand, six hundred thirty-four".