261505986 has 32 divisors (see below), whose sum is σ = 603899520. Its totient is φ = 73944576.

The previous prime is 261505969. The next prime is 261505991. The reversal of 261505986 is 689505162.

261505986 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28021 + ... + 36168.

It is an arithmetic number, because the mean of its divisors is an integer number (18871860).

Almost surely, 2^261505986 is an apocalyptic number.

261505986 is an abundant number, since it is smaller than the sum of its proper divisors (342393534).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261505986 is a wasteful number, since it uses less digits than its factorization.

261505986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64298.

The product of its (nonzero) digits is 129600, while the sum is 42.

The square root of 261505986 is about 16171.1467125866. The cubic root of 261505986 is about 639.4803610783.

The spelling of 261505986 in words is "two hundred sixty-one million, five hundred five thousand, nine hundred eighty-six".