3121271561 has 4 divisors (see below), whose sum is σ = 3126363972. Its totient is φ = 3116179152.

The previous prime is 3121271539. The next prime is 3121271597. The reversal of 3121271561 is 1651721213.

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 493683961 + 2627587600 = 22219^2 + 51260^2 .

It is a cyclic number.

It is not a de Polignac number, because 3121271561 - 2¹⁴ = 3121255177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3121271501) 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, 2545286 + ... + 2546511.

It is an arithmetic number, because the mean of its divisors is an integer number (781590993).

Almost surely, 2^3121271561 is an apocalyptic number.

It is an amenable number.

3121271561 is a deficient number, since it is larger than the sum of its proper divisors (5092411).

3121271561 is an equidigital number, since it uses as much as digits as its factorization.

3121271561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5092410.

The product of its digits is 2520, while the sum is 29.

The square root of 3121271561 is about 55868.3413124106. The cubic root of 3121271561 is about 1461.4271965526.

Adding to 3121271561 its reverse (1651721213), we get a palindrome (4772992774).

The spelling of 3121271561 in words is "three billion, one hundred twenty-one million, two hundred seventy-one thousand, five hundred sixty-one".