261121405 has 4 divisors (see below), whose sum is σ = 313345692. Its totient is φ = 208897120.

The previous prime is 261121379. The next prime is 261121429. The reversal of 261121405 is 504121162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 33051001 + 228070404 = 5749^2 + 15102^2 .

It is not a de Polignac number, because 261121405 - 2⁵ = 261121373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26112136 + ... + 26112145.

It is an arithmetic number, because the mean of its divisors is an integer number (78336423).

Almost surely, 2^261121405 is an apocalyptic number.

It is an amenable number.

261121405 is a deficient number, since it is larger than the sum of its proper divisors (52224287).

261121405 is an equidigital number, since it uses as much as digits as its factorization.

261121405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52224286.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 261121405 is about 16159.2513749864. The cubic root of 261121405 is about 639.1667256135.

Adding to 261121405 its reverse (504121162), we get a palindrome (765242567).

The spelling of 261121405 in words is "two hundred sixty-one million, one hundred twenty-one thousand, four hundred five".