631135561781 has 4 divisors (see below), whose sum is σ = 631186239372. Its totient is φ = 631084884192.

The previous prime is 631135561769. The next prime is 631135561783. The reversal of 631135561781 is 187165531136.

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 551588436100 + 79547125681 = 742690^2 + 282041^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-631135561781 is a prime.

It is a super-2 number, since 2×631135561781² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (631135561783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25320110 + ... + 25345023.

It is an arithmetic number, because the mean of its divisors is an integer number (157796559843).

Almost surely, 2^631135561781 is an apocalyptic number.

It is an amenable number.

631135561781 is a deficient number, since it is larger than the sum of its proper divisors (50677591).

631135561781 is a wasteful number, since it uses less digits than its factorization.

631135561781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50677590.

The product of its digits is 453600, while the sum is 47.

The spelling of 631135561781 in words is "six hundred thirty-one billion, one hundred thirty-five million, five hundred sixty-one thousand, seven hundred eighty-one".