31143847721 has 6 divisors (see below), whose sum is σ = 36228557610. Its totient is φ = 26694726576.

The previous prime is 31143847703. The next prime is 31143847729. The reversal of 31143847721 is 12774834113.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 29287530496 + 1856317225 = 171136^2 + 43085^2 .

It is not a de Polignac number, because 31143847721 - 2¹⁴ = 31143831337 is a prime.

It is not an unprimeable number, because it can be changed into a prime (31143847729) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 317794316 + ... + 317794413.

It is an arithmetic number, because the mean of its divisors is an integer number (6038092935).

Almost surely, 2^31143847721 is an apocalyptic number.

It is an amenable number.

31143847721 is a deficient number, since it is larger than the sum of its proper divisors (5084709889).

31143847721 is an equidigital number, since it uses as much as digits as its factorization.

31143847721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 635588743 (or 635588736 counting only the distinct ones).

The product of its digits is 112896, while the sum is 41.

The spelling of 31143847721 in words is "thirty-one billion, one hundred forty-three million, eight hundred forty-seven thousand, seven hundred twenty-one".