31257961542721 has 4 divisors (see below), whose sum is σ = 31770387141844. Its totient is φ = 30745535943600.

The previous prime is 31257961542719. The next prime is 31257961542727. The reversal of 31257961542721 is 12724516975213.

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 1419109917696 + 29838851625025 = 1191264^2 + 5462495^2 .

It is a cyclic number.

It is not a de Polignac number, because 31257961542721 - 2¹ = 31257961542719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31257961542727) 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, 256212799470 + ... + 256212799591.

It is an arithmetic number, because the mean of its divisors is an integer number (7942596785461).

Almost surely, 2^{31257961542721} is an apocalyptic number.

It is an amenable number.

31257961542721 is a deficient number, since it is larger than the sum of its proper divisors (512425599123).

31257961542721 is an equidigital number, since it uses as much as digits as its factorization.

31257961542721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512425599122.

The product of its digits is 6350400, while the sum is 55.

The spelling of 31257961542721 in words is "thirty-one trillion, two hundred fifty-seven billion, nine hundred sixty-one million, five hundred forty-two thousand, seven hundred twenty-one".