31550143981 has 2 divisors, whose sum is σ = 31550143982. Its totient is φ = 31550143980.

The previous prime is 31550143979. The next prime is 31550144027. The reversal of 31550143981 is 18934105513.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30712562500 + 837581481 = 175250^2 + 28941^2 .

It is a cyclic number.

It is not a de Polignac number, because 31550143981 - 2¹ = 31550143979 is a prime.

It is a super-2 number, since 2×31550143981² (a number of 22 digits) contains 22 as substring.

Together with 31550143979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31550143921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15775071990 + 15775071991.

It is an arithmetic number, because the mean of its divisors is an integer number (15775071991).

Almost surely, 2^31550143981 is an apocalyptic number.

It is an amenable number.

31550143981 is a deficient number, since it is larger than the sum of its proper divisors (1).

31550143981 is an equidigital number, since it uses as much as digits as its factorization.

31550143981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64800, while the sum is 40.

The spelling of 31550143981 in words is "thirty-one billion, five hundred fifty million, one hundred forty-three thousand, nine hundred eighty-one".