145206221561 has 4 divisors (see below), whose sum is σ = 145376452452. Its totient is φ = 145035990672.

The previous prime is 145206221527. The next prime is 145206221591. The reversal of 145206221561 is 165122602541.

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 66543361600 + 78662859961 = 257960^2 + 280469^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-145206221561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (145206221591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85114166 + ... + 85115871.

It is an arithmetic number, because the mean of its divisors is an integer number (36344113113).

Almost surely, 2^145206221561 is an apocalyptic number.

It is an amenable number.

145206221561 is a deficient number, since it is larger than the sum of its proper divisors (170230891).

145206221561 is an equidigital number, since it uses as much as digits as its factorization.

145206221561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170230890.

The product of its (nonzero) digits is 28800, while the sum is 35.

The spelling of 145206221561 in words is "one hundred forty-five billion, two hundred six million, two hundred twenty-one thousand, five hundred sixty-one".