261940861 has 16 divisors (see below), whose sum is σ = 323137024. Its totient is φ = 206769024.

The previous prime is 261940831. The next prime is 261940867. The reversal of 261940861 is 168049162.

It is a happy number.

It is not a de Polignac number, because 261940861 - 2⁵ = 261940829 is a prime.

It is a super-2 number, since 2×261940861² = 137226029322842642, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 261940861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261940867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39025 + ... + 45241.

It is an arithmetic number, because the mean of its divisors is an integer number (20196064).

Almost surely, 2^261940861 is an apocalyptic number.

It is an amenable number.

261940861 is a deficient number, since it is larger than the sum of its proper divisors (61196163).

261940861 is a wasteful number, since it uses less digits than its factorization.

261940861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6700.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 261940861 is about 16184.5871433287. The cubic root of 261940861 is about 639.8346423386.

The spelling of 261940861 in words is "two hundred sixty-one million, nine hundred forty thousand, eight hundred sixty-one".