245131561 has 4 divisors (see below), whose sum is σ = 245188692. Its totient is φ = 245074432.

The previous prime is 245131553. The next prime is 245131573. The reversal of 245131561 is 165131542.

245131561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165131542 = 2 ⋅82565771.

It can be written as a sum of positive squares in 2 ways, for example, as 241615936 + 3515625 = 15544^2 + 1875^2 .

It is a cyclic number.

It is not a de Polignac number, because 245131561 - 2³ = 245131553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (245131541) 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, 21556 + ... + 30901.

It is an arithmetic number, because the mean of its divisors is an integer number (61297173).

Almost surely, 2^245131561 is an apocalyptic number.

It is an amenable number.

245131561 is a deficient number, since it is larger than the sum of its proper divisors (57131).

245131561 is an equidigital number, since it uses as much as digits as its factorization.

245131561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57130.

The product of its digits is 3600, while the sum is 28.

The square root of 245131561 is about 15656.6778404616. The cubic root of 245131561 is about 625.8444572333.

The spelling of 245131561 in words is "two hundred forty-five million, one hundred thirty-one thousand, five hundred sixty-one".