261220520121 has 48 divisors (see below), whose sum is σ = 392892445440. Its totient is φ = 153098013600.

The previous prime is 261220520117. The next prime is 261220520161. The reversal of 261220520121 is 121025022162.

It is not a de Polignac number, because 261220520121 - 2² = 261220520117 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 261220520091 and 261220520100.

It is not an unprimeable number, because it can be changed into a prime (261220520101) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 69861870 + ... + 69865608.

It is an arithmetic number, because the mean of its divisors is an integer number (8185259280).

Almost surely, 2^261220520121 is an apocalyptic number.

It is an amenable number.

261220520121 is a deficient number, since it is larger than the sum of its proper divisors (131671925319).

261220520121 is a wasteful number, since it uses less digits than its factorization.

261220520121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6018 (or 5987 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

Adding to 261220520121 its reverse (121025022162), we get a palindrome (382245542283).

The spelling of 261220520121 in words is "two hundred sixty-one billion, two hundred twenty million, five hundred twenty thousand, one hundred twenty-one".