261561377 has 16 divisors (see below), whose sum is σ = 326556672. Its totient is φ = 203530320.

The previous prime is 261561347. The next prime is 261561379. The reversal of 261561377 is 773165162.

261561377 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 261561377 - 2¹² = 261557281 is a prime.

It is a super-2 number, since 2×261561377² = 136828707876272258, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261561377.

It is not an unprimeable number, because it can be changed into a prime (261561379) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66068 + ... + 69914.

It is an arithmetic number, because the mean of its divisors is an integer number (20409792).

Almost surely, 2^261561377 is an apocalyptic number.

It is an amenable number.

261561377 is a deficient number, since it is larger than the sum of its proper divisors (64995295).

261561377 is a wasteful number, since it uses less digits than its factorization.

261561377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4748.

The product of its digits is 52920, while the sum is 38.

The square root of 261561377 is about 16172.8592710133. The cubic root of 261561377 is about 639.5255084911.

The spelling of 261561377 in words is "two hundred sixty-one million, five hundred sixty-one thousand, three hundred seventy-seven".