261665044101510 has 256 divisors, whose sum is σ = 733548480749568. Its totient is φ = 58500517017600.

The previous prime is 261665044101479. The next prime is 261665044101541. The reversal of 261665044101510 is 15101440566162.

It is an interprime number because it is at equal distance from previous prime (261665044101479) and next prime (261665044101541).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 5206099780 + ... + 5206150040.

It is an arithmetic number, because the mean of its divisors is an integer number (2865423752928).

Almost surely, 2^{261665044101510} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261665044101510, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (366774240374784).

261665044101510 is an abundant number, since it is smaller than the sum of its proper divisors (471883436648058).

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

261665044101510 is a wasteful number, since it uses less digits than its factorization.

261665044101510 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52599.

The product of its (nonzero) digits is 172800, while the sum is 42.

Adding to 261665044101510 its reverse (15101440566162), we get a palindrome (276766484667672).

The spelling of 261665044101510 in words is "two hundred sixty-one trillion, six hundred sixty-five billion, forty-four million, one hundred one thousand, five hundred ten".