261978 has 16 divisors (see below), whose sum is σ = 535680. Its totient is φ = 85376.

The previous prime is 261977. The next prime is 261983. The reversal of 261978 is 879162.

261978 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a nialpdrome in base 8.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261971) 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, 183 + ... + 746.

It is an arithmetic number, because the mean of its divisors is an integer number (33480).

2²⁶¹⁹⁷⁸ is an apocalyptic number.

261978 is an abundant number, since it is smaller than the sum of its proper divisors (273702).

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

261978 is a wasteful number, since it uses less digits than its factorization.

261978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 981.

The product of its digits is 6048, while the sum is 33.

The square root of 261978 is about 511.8378649533. The cubic root of 261978 is about 63.9864880329.

The spelling of 261978 in words is "two hundred sixty-one thousand, nine hundred seventy-eight".