31561105 has 4 divisors (see below), whose sum is σ = 37873332. Its totient is φ = 25248880.

The previous prime is 31561099. The next prime is 31561121. The reversal of 31561105 is 50116513.

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 6230016 + 25331089 = 2496^2 + 5033^2 .

It is not a de Polignac number, because 31561105 - 2¹⁵ = 31528337 is a prime.

It is a super-2 number, since 2×31561105² = 1992206697642050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3156106 + ... + 3156115.

It is an arithmetic number, because the mean of its divisors is an integer number (9468333).

Almost surely, 2^31561105 is an apocalyptic number.

It is an amenable number.

31561105 is a deficient number, since it is larger than the sum of its proper divisors (6312227).

31561105 is an equidigital number, since it uses as much as digits as its factorization.

31561105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6312226.

The product of its (nonzero) digits is 450, while the sum is 22.

The square root of 31561105 is about 5617.9271088187. The cubic root of 31561105 is about 316.0220602289.

Adding to 31561105 its reverse (50116513), we get a palindrome (81677618).

The spelling of 31561105 in words is "thirty-one million, five hundred sixty-one thousand, one hundred five".