261551501065 has 4 divisors (see below), whose sum is σ = 313861801284. Its totient is φ = 209241200848.

The previous prime is 261551501059. The next prime is 261551501069. The reversal of 261551501065 is 560105155162.

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 139887968256 + 121663532809 = 374016^2 + 348803^2 .

It is a cyclic number.

It is not a de Polignac number, because 261551501065 - 2³¹ = 259404017417 is a prime.

It is a super-2 number, since 2×261551501065² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261551501069) 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, 26155150102 + ... + 26155150111.

It is an arithmetic number, because the mean of its divisors is an integer number (78465450321).

Almost surely, 2^261551501065 is an apocalyptic number.

It is an amenable number.

261551501065 is a deficient number, since it is larger than the sum of its proper divisors (52310300219).

261551501065 is an equidigital number, since it uses as much as digits as its factorization.

261551501065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52310300218.

The product of its (nonzero) digits is 45000, while the sum is 37.

The spelling of 261551501065 in words is "two hundred sixty-one billion, five hundred fifty-one million, five hundred one thousand, sixty-five".