261543156 has 96 divisors (see below), whose sum is σ = 735608832. Its totient is φ = 70744320.

The previous prime is 261543103. The next prime is 261543169. The reversal of 261543156 is 651345162.

It is a congruent number.

It is an unprimeable number.

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, 121320 + ... + 123456.

It is an arithmetic number, because the mean of its divisors is an integer number (7662592).

Almost surely, 2^261543156 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 261543156, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (367804416).

261543156 is an abundant number, since it is smaller than the sum of its proper divisors (474065676).

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

261543156 is a wasteful number, since it uses less digits than its factorization.

261543156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2229 (or 2227 counting only the distinct ones).

The product of its digits is 21600, while the sum is 33.

The square root of 261543156 is about 16172.2959408984. The cubic root of 261543156 is about 639.5106578468.

The spelling of 261543156 in words is "two hundred sixty-one million, five hundred forty-three thousand, one hundred fifty-six".