63731981 has 2 divisors, whose sum is σ = 63731982. Its totient is φ = 63731980.

The previous prime is 63731959. The next prime is 63732017. The reversal of 63731981 is 18913736.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62267881 + 1464100 = 7891^2 + 1210^2 .

It is a cyclic number.

It is not a de Polignac number, because 63731981 - 2¹⁰ = 63730957 is a prime.

It is a super-2 number, since 2×63731981² = 8123530804368722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (63731911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 31865990 + 31865991.

It is an arithmetic number, because the mean of its divisors is an integer number (31865991).

Almost surely, 2^63731981 is an apocalyptic number.

It is an amenable number.

63731981 is a deficient number, since it is larger than the sum of its proper divisors (1).

63731981 is an equidigital number, since it uses as much as digits as its factorization.

63731981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 38.

The square root of 63731981 is about 7983.2312380389. The cubic root of 63731981 is about 399.4408458140.

The spelling of 63731981 in words is "sixty-three million, seven hundred thirty-one thousand, nine hundred eighty-one".