31551121205 has 4 divisors (see below), whose sum is σ = 37861345452. Its totient is φ = 25240896960.

The previous prime is 31551121201. The next prime is 31551121211. The reversal of 31551121205 is 50212115513.

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 16867255876 + 14683865329 = 129874^2 + 121177^2 .

It is not a de Polignac number, because 31551121205 - 2² = 31551121201 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31551121201) 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, 3155112116 + ... + 3155112125.

It is an arithmetic number, because the mean of its divisors is an integer number (9465336363).

Almost surely, 2^31551121205 is an apocalyptic number.

It is an amenable number.

31551121205 is a deficient number, since it is larger than the sum of its proper divisors (6310224247).

31551121205 is an equidigital number, since it uses as much as digits as its factorization.

31551121205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6310224246.

The product of its (nonzero) digits is 1500, while the sum is 26.

Adding to 31551121205 its reverse (50212115513), we get a palindrome (81763236718).

The spelling of 31551121205 in words is "thirty-one billion, five hundred fifty-one million, one hundred twenty-one thousand, two hundred five".