165225025261 has 4 divisors (see below), whose sum is σ = 174944144412. Its totient is φ = 155505906112.

The previous prime is 165225025253. The next prime is 165225025279. The reversal of 165225025261 is 162520522561.

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 80503280361 + 84721744900 = 283731^2 + 291070^2 .

It is a cyclic number.

It is not a de Polignac number, because 165225025261 - 2³ = 165225025253 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 165225025261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165225025211) 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, 4859559550 + ... + 4859559583.

It is an arithmetic number, because the mean of its divisors is an integer number (43736036103).

Almost surely, 2^165225025261 is an apocalyptic number.

It is an amenable number.

165225025261 is a deficient number, since it is larger than the sum of its proper divisors (9719119151).

165225025261 is an equidigital number, since it uses as much as digits as its factorization.

165225025261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9719119150.

The product of its (nonzero) digits is 72000, while the sum is 37.

The spelling of 165225025261 in words is "one hundred sixty-five billion, two hundred twenty-five million, twenty-five thousand, two hundred sixty-one".