261321552 has 200 divisors, whose sum is σ = 830471400. Its totient is φ = 78962688.

The previous prime is 261321547. The next prime is 261321553. The reversal of 261321552 is 255123162.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 133541136 + 127780416 = 11556^2 + 11304^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261321553) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 638724 + ... + 639132.

It is an arithmetic number, because the mean of its divisors is an integer number (4152357).

Almost surely, 2^261321552 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261321552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (415235700).

261321552 is an abundant number, since it is smaller than the sum of its proper divisors (569149848).

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

261321552 is a wasteful number, since it uses less digits than its factorization.

261321552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475 (or 460 counting only the distinct ones).

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

The square root of 261321552 is about 16165.4431427041. The cubic root of 261321552 is about 639.3299889195.

The spelling of 261321552 in words is "two hundred sixty-one million, three hundred twenty-one thousand, five hundred fifty-two".