261430421304520 has 256 divisors, whose sum is σ = 669251838689280. Its totient is φ = 91222221081600.

The previous prime is 261430421304499. The next prime is 261430421304659. The reversal of 261430421304520 is 25403124034162.

It is a self number, because there is not a number n which added to its sum of digits gives 261430421304520.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3417933717 + ... + 3418010203.

It is an arithmetic number, because the mean of its divisors is an integer number (2614264994880).

Almost surely, 2^{261430421304520} is an apocalyptic number.

261430421304520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261430421304520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (334625919344640).

261430421304520 is an abundant number, since it is smaller than the sum of its proper divisors (407821417384760).

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

261430421304520 is a wasteful number, since it uses less digits than its factorization.

261430421304520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81516 (or 81512 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 37.

Adding to 261430421304520 its reverse (25403124034162), we get a palindrome (286833545338682).

The spelling of 261430421304520 in words is "two hundred sixty-one trillion, four hundred thirty billion, four hundred twenty-one million, three hundred four thousand, five hundred twenty".