261615646 has 16 divisors (see below), whose sum is σ = 396316800. Its totient is φ = 129514840.

The previous prime is 261615643. The next prime is 261615647. The reversal of 261615646 is 646516162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261615643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 156105 + ... + 157771.

It is an arithmetic number, because the mean of its divisors is an integer number (24769800).

Almost surely, 2^261615646 is an apocalyptic number.

261615646 is a deficient number, since it is larger than the sum of its proper divisors (134701154).

261615646 is a wasteful number, since it uses less digits than its factorization.

261615646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2399.

The product of its digits is 51840, while the sum is 37.

The square root of 261615646 is about 16174.5369640061. The cubic root of 261615646 is about 639.5697352167.

The spelling of 261615646 in words is "two hundred sixty-one million, six hundred fifteen thousand, six hundred forty-six".