261317165420 has 24 divisors (see below), whose sum is σ = 548882190864. Its totient is φ = 104504743616.

The previous prime is 261317165387. The next prime is 261317165423. The reversal of 261317165420 is 24561713162.

It is not an unprimeable number, because it can be changed into a prime (261317165423) 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, 1285634 + ... + 1474953.

It is an arithmetic number, because the mean of its divisors is an integer number (22870091286).

Almost surely, 2^261317165420 is an apocalyptic number.

261317165420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261317165420 is an abundant number, since it is smaller than the sum of its proper divisors (287565025444).

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

261317165420 is a wasteful number, since it uses less digits than its factorization.

261317165420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2765329 (or 2765327 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 38.

Adding to 261317165420 its reverse (24561713162), we get a palindrome (285878878582).

The spelling of 261317165420 in words is "two hundred sixty-one billion, three hundred seventeen million, one hundred sixty-five thousand, four hundred twenty".