261806157 has 12 divisors (see below), whose sum is σ = 379639260. Its totient is φ = 173856768.

The previous prime is 261806143. The next prime is 261806159. The reversal of 261806157 is 751608162.

261806157 is a `hidden beast` number, since 26 + 18 + 0 + 615 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 202037796 + 59768361 = 14214^2 + 7731^2 .

It is not a de Polignac number, because 261806157 - 2⁶ = 261806093 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261806159) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 54282 + ... + 58907.

It is an arithmetic number, because the mean of its divisors is an integer number (31636605).

Almost surely, 2^261806157 is an apocalyptic number.

It is an amenable number.

261806157 is a deficient number, since it is larger than the sum of its proper divisors (117833103).

261806157 is a wasteful number, since it uses less digits than its factorization.

261806157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113452 (or 113449 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 261806157 is about 16180.4251180246. The cubic root of 261806157 is about 639.7249444679.

The spelling of 261806157 in words is "two hundred sixty-one million, eight hundred six thousand, one hundred fifty-seven".