2031731561 has 4 divisors (see below), whose sum is σ = 2101791300. Its totient is φ = 1961671824.

The previous prime is 2031731543. The next prime is 2031731563. The reversal of 2031731561 is 1651371302.

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 1742561536 + 289170025 = 41744^2 + 17005^2 .

It is a de Polignac number, because none of the positive numbers 2^k-2031731561 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 70059709 = 2031731561 / (2 + 0 + 3 + 1 + 7 + 3 + 1 + 5 + 6 + 1).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2031731563) 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, 35029826 + ... + 35029883.

It is an arithmetic number, because the mean of its divisors is an integer number (525447825).

Almost surely, 2^2031731561 is an apocalyptic number.

It is an amenable number.

2031731561 is a deficient number, since it is larger than the sum of its proper divisors (70059739).

2031731561 is an equidigital number, since it uses as much as digits as its factorization.

2031731561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70059738.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 2031731561 is about 45074.7330663200. The cubic root of 2031731561 is about 1266.5493285197.

The spelling of 2031731561 in words is "two billion, thirty-one million, seven hundred thirty-one thousand, five hundred sixty-one".