261841821 has 8 divisors (see below), whose sum is σ = 364301760. Its totient is φ = 166971552.

The previous prime is 261841813. The next prime is 261841861. The reversal of 261841821 is 128148162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 261841821 - 2³ = 261841813 is a prime.

It is a super-2 number, since 2×261841821² = 137122278449192082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261841861) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1897336 + ... + 1897473.

It is an arithmetic number, because the mean of its divisors is an integer number (45537720).

Almost surely, 2^261841821 is an apocalyptic number.

It is an amenable number.

261841821 is a deficient number, since it is larger than the sum of its proper divisors (102459939).

261841821 is a wasteful number, since it uses less digits than its factorization.

261841821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3794835.

The product of its digits is 6144, while the sum is 33.

The square root of 261841821 is about 16181.5271528988. The cubic root of 261841821 is about 639.7539915496.

Adding to 261841821 its reverse (128148162), we get a palindrome (389989983).

The spelling of 261841821 in words is "two hundred sixty-one million, eight hundred forty-one thousand, eight hundred twenty-one".