261378656 has 192 divisors, whose sum is σ = 683956224. Its totient is φ = 95385600.

The previous prime is 261378643. The next prime is 261378679. The reversal of 261378656 is 656873162.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4284866 + ... + 4284926.

It is an arithmetic number, because the mean of its divisors is an integer number (3562272).

Almost surely, 2^261378656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261378656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (341978112).

261378656 is an abundant number, since it is smaller than the sum of its proper divisors (422577568).

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

261378656 is a wasteful number, since it uses less digits than its factorization.

261378656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 165 counting only the distinct ones).

The product of its digits is 362880, while the sum is 44.

The square root of 261378656 is about 16167.2092829901. The cubic root of 261378656 is about 639.3765543360.

The spelling of 261378656 in words is "two hundred sixty-one million, three hundred seventy-eight thousand, six hundred fifty-six".