31381735729 has 2 divisors, whose sum is σ = 31381735730. Its totient is φ = 31381735728.

The previous prime is 31381735717. The next prime is 31381735807. The reversal of 31381735729 is 92753718313.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29713830129 + 1667905600 = 172377^2 + 40840^2 .

It is a cyclic number.

It is not a de Polignac number, because 31381735729 - 2²³ = 31373347121 is a prime.

It is a super-2 number, since 2×31381735729² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31381735709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15690867864 + 15690867865.

It is an arithmetic number, because the mean of its divisors is an integer number (15690867865).

Almost surely, 2^31381735729 is an apocalyptic number.

It is an amenable number.

31381735729 is a deficient number, since it is larger than the sum of its proper divisors (1).

31381735729 is an equidigital number, since it uses as much as digits as its factorization.

31381735729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 952560, while the sum is 49.

The spelling of 31381735729 in words is "thirty-one billion, three hundred eighty-one million, seven hundred thirty-five thousand, seven hundred twenty-nine".