261161906 has 8 divisors (see below), whose sum is σ = 391855260. Its totient is φ = 130543488.

The previous prime is 261161903. The next prime is 261161921. The reversal of 261161906 is 609161162.

It can be written as a sum of positive squares in 2 ways, for example, as 247905025 + 13256881 = 15745^2 + 3641^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×261161906² = 136411082291105672, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261161903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9011 + ... + 24566.

Almost surely, 2^261161906 is an apocalyptic number.

261161906 is a deficient number, since it is larger than the sum of its proper divisors (130693354).

261161906 is a wasteful number, since it uses less digits than its factorization.

261161906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37468.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 261161906 is about 16160.5045094514. The cubic root of 261161906 is about 639.1997696980.

The spelling of 261161906 in words is "two hundred sixty-one million, one hundred sixty-one thousand, nine hundred six".