261020628066 has 64 divisors (see below), whose sum is σ = 577463302656. Its totient is φ = 77991696000.

The previous prime is 261020628061. The next prime is 261020628101. The reversal of 261020628066 is 660826020162.

It is not an unprimeable number, because it can be changed into a prime (261020628061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 27221725 + ... + 27231311.

It is an arithmetic number, because the mean of its divisors is an integer number (9022864104).

Almost surely, 2^261020628066 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261020628066, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (288731651328).

261020628066 is an abundant number, since it is smaller than the sum of its proper divisors (316442674590).

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

261020628066 is a wasteful number, since it uses less digits than its factorization.

261020628066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15327.

The product of its (nonzero) digits is 82944, while the sum is 39.

It can be divided in two parts, 2610 and 20628066, that added together give a triangular number (20630676 = T₆₄₂₃).

The spelling of 261020628066 in words is "two hundred sixty-one billion, twenty million, six hundred twenty-eight thousand, sixty-six".