261677988864 has 132 divisors (see below), whose sum is σ = 757625175736. Its totient is φ = 86991003648.

The previous prime is 261677988829. The next prime is 261677988983. The reversal of 261677988864 is 468889776162.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 261677988792 and 261677988801.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3399507 + ... + 3475629.

Almost surely, 2^261677988864 is an apocalyptic number.

261677988864 is a gapful number since it is divisible by the number (24) 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 261677988864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (378812587868).

261677988864 is an abundant number, since it is smaller than the sum of its proper divisors (495947186872).

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

261677988864 is a wasteful number, since it uses less digits than its factorization.

261677988864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76522 (or 76501 counting only the distinct ones).

The product of its digits is 390168576, while the sum is 72.

The spelling of 261677988864 in words is "two hundred sixty-one billion, six hundred seventy-seven million, nine hundred eighty-eight thousand, eight hundred sixty-four".