245664671561 has 4 divisors (see below), whose sum is σ = 260115534612. Its totient is φ = 231213808512.

The previous prime is 245664671531. The next prime is 245664671569. The reversal of 245664671561 is 165176466542.

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 82868561161 + 162796110400 = 287869^2 + 403480^2 .

It is a cyclic number.

It is not a de Polignac number, because 245664671561 - 2²⁶ = 245597562697 is a prime.

It is a super-2 number, since 2×245664671561² (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 (245664671569) 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, 7225431500 + ... + 7225431533.

It is an arithmetic number, because the mean of its divisors is an integer number (65028883653).

Almost surely, 2^245664671561 is an apocalyptic number.

It is an amenable number.

245664671561 is a deficient number, since it is larger than the sum of its proper divisors (14450863051).

245664671561 is a wasteful number, since it uses less digits than its factorization.

245664671561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14450863050.

The product of its digits is 7257600, while the sum is 53.

The spelling of 245664671561 in words is "two hundred forty-five billion, six hundred sixty-four million, six hundred seventy-one thousand, five hundred sixty-one".