165456554253721 has 4 divisors (see below), whose sum is σ = 175189292739252. Its totient is φ = 155723815768192.

The previous prime is 165456554253709. The next prime is 165456554253839. The reversal of 165456554253721 is 127352455654561.

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 153636297690121 + 11820256563600 = 12395011^2 + 3438060^2 .

It is a cyclic number.

It is not a de Polignac number, because 165456554253721 - 2¹⁷ = 165456554122649 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 165456554253721.

It is not an unprimeable number, because it can be changed into a prime (165456554253701) 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, 4866369242740 + ... + 4866369242773.

It is an arithmetic number, because the mean of its divisors is an integer number (43797323184813).

Almost surely, 2^{165456554253721} is an apocalyptic number.

It is an amenable number.

165456554253721 is a deficient number, since it is larger than the sum of its proper divisors (9732738485531).

165456554253721 is an equidigital number, since it uses as much as digits as its factorization.

165456554253721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9732738485530.

The product of its digits is 151200000, while the sum is 61.

The spelling of 165456554253721 in words is "one hundred sixty-five trillion, four hundred fifty-six billion, five hundred fifty-four million, two hundred fifty-three thousand, seven hundred twenty-one".