261086288021 has 16 divisors (see below), whose sum is σ = 290988726000. Its totient is φ = 232593596928.

The previous prime is 261086288017. The next prime is 261086288051. The reversal of 261086288021 is 120882680162.

It can be written as a sum of positive squares in 8 ways, for example, as 82820781796 + 178265506225 = 287786^2 + 422215^2 .

It is a cyclic number.

It is not a de Polignac number, because 261086288021 - 2² = 261086288017 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261086288011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 750455 + ... + 1041803.

It is an arithmetic number, because the mean of its divisors is an integer number (18186795375).

Almost surely, 2^261086288021 is an apocalyptic number.

It is an amenable number.

261086288021 is a deficient number, since it is larger than the sum of its proper divisors (29902437979).

261086288021 is a wasteful number, since it uses less digits than its factorization.

261086288021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 293768.

The product of its (nonzero) digits is 147456, while the sum is 44.

The spelling of 261086288021 in words is "two hundred sixty-one billion, eighty-six million, two hundred eighty-eight thousand, twenty-one".