261811380 has 24 divisors (see below), whose sum is σ = 733072032. Its totient is φ = 69816352.

The previous prime is 261811343. The next prime is 261811397. The reversal of 261811380 is 83118162.

It is a Harshad number since it is a multiple of its sum of digits (30).

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 7 ways as a sum of consecutive naturals, for example, 2181702 + ... + 2181821.

It is an arithmetic number, because the mean of its divisors is an integer number (30544668).

Almost surely, 2^261811380 is an apocalyptic number.

261811380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261811380 is an abundant number, since it is smaller than the sum of its proper divisors (471260652).

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

261811380 is a wasteful number, since it uses less digits than its factorization.

261811380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4363535 (or 4363533 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 261811380 is about 16180.5865159456. The cubic root of 261811380 is about 639.7291985838.

The spelling of 261811380 in words is "two hundred sixty-one million, eight hundred eleven thousand, three hundred eighty".