261770521894561 has 4 divisors (see below), whose sum is σ = 261794802632724. Its totient is φ = 261746241156400.

The previous prime is 261770521894543. The next prime is 261770521894603. The reversal of 261770521894561 is 165498125077162.

It is a happy number.

261770521894561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 175688662657600 + 86081859236961 = 13254760^2 + 9278031^2 .

It is a cyclic number.

It is not a de Polignac number, because 261770521894561 - 2⁴¹ = 259571498639009 is a prime.

It is a super-2 number, since 2×261770521894561² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261770521894493 and 261770521894502.

It is not an unprimeable number, because it can be changed into a prime (261770521894261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12140352910 + ... + 12140374471.

It is an arithmetic number, because the mean of its divisors is an integer number (65448700658181).

Almost surely, 2^{261770521894561} is an apocalyptic number.

It is an amenable number.

261770521894561 is a deficient number, since it is larger than the sum of its proper divisors (24280738163).

261770521894561 is a wasteful number, since it uses less digits than its factorization.

261770521894561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24280738162.

The product of its (nonzero) digits is 50803200, while the sum is 64.

The spelling of 261770521894561 in words is "two hundred sixty-one trillion, seven hundred seventy billion, five hundred twenty-one million, eight hundred ninety-four thousand, five hundred sixty-one".