261645378 has 16 divisors (see below), whose sum is σ = 546042816. Its totient is φ = 83423120.

The previous prime is 261645347. The next prime is 261645379. The reversal of 261645378 is 873546162.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (261645379) 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, 947853 + ... + 948128.

It is an arithmetic number, because the mean of its divisors is an integer number (34127676).

Almost surely, 2^261645378 is an apocalyptic number.

261645378 is an abundant number, since it is smaller than the sum of its proper divisors (284397438).

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

261645378 is a wasteful number, since it uses less digits than its factorization.

261645378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1896009.

The product of its digits is 241920, while the sum is 42.

The square root of 261645378 is about 16175.4560368479. The cubic root of 261645378 is about 639.5939628287.

The spelling of 261645378 in words is "two hundred sixty-one million, six hundred forty-five thousand, three hundred seventy-eight".