261841820 has 24 divisors (see below), whose sum is σ = 582213744. Its totient is φ = 98575616.

The previous prime is 261841813. The next prime is 261841861. The reversal of 261841820 is 28148162.

It is a happy number.

It is a super-2 number, since 2×261841820² = 137122277401824800, which contains 22 as substring.

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, 384722 + ... + 385401.

It is an arithmetic number, because the mean of its divisors is an integer number (24258906).

Almost surely, 2^261841820 is an apocalyptic number.

261841820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261841820 is an abundant number, since it is smaller than the sum of its proper divisors (320371924).

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

261841820 is a wasteful number, since it uses less digits than its factorization.

261841820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 770149 (or 770147 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 32.

The square root of 261841820 is about 16181.5271219993. The cubic root of 261841820 is about 639.7539907352.

Adding to 261841820 its reverse (28148162), we get a palindrome (289989982).

The spelling of 261841820 in words is "two hundred sixty-one million, eight hundred forty-one thousand, eight hundred twenty".