261655020 has 144 divisors (see below), whose sum is σ = 874927872. Its totient is φ = 62766720.

The previous prime is 261655019. The next prime is 261655021. The reversal of 261655020 is 20556162.

261655020 is a `hidden beast` number, since 2 + 6 + 1 + 655 + 0 + 2 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (261655019) and next prime (261655021).

It is not an unprimeable number, because it can be changed into a prime (261655021) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 203299 + ... + 204581.

It is an arithmetic number, because the mean of its divisors is an integer number (6075888).

Almost surely, 2^261655020 is an apocalyptic number.

261655020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261655020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (437463936).

261655020 is an abundant number, since it is smaller than the sum of its proper divisors (613272852).

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

261655020 is a wasteful number, since it uses less digits than its factorization.

261655020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1412 (or 1407 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 261655020 is about 16175.7540782493. The cubic root of 261655020 is about 639.6018193777.

The spelling of 261655020 in words is "two hundred sixty-one million, six hundred fifty-five thousand, twenty".