63881981 has 2 divisors, whose sum is σ = 63881982. Its totient is φ = 63881980.

The previous prime is 63881953. The next prime is 63882011. The reversal of 63881981 is 18918836.

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., 50993881 + 12888100 = 7141^2 + 3590^2 .

It is a cyclic number.

It is not a de Polignac number, because 63881981 - 2¹⁸ = 63619837 is a prime.

It is a super-2 number, since 2×63881981² = 8161814992968722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (63881681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 31940990 + 31940991.

It is an arithmetic number, because the mean of its divisors is an integer number (31940991).

Almost surely, 2^63881981 is an apocalyptic number.

It is an amenable number.

63881981 is a deficient number, since it is larger than the sum of its proper divisors (1).

63881981 is an equidigital number, since it uses as much as digits as its factorization.

63881981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 44.

The square root of 63881981 is about 7992.6204088522. The cubic root of 63881981 is about 399.7539757946.

The spelling of 63881981 in words is "sixty-three million, eight hundred eighty-one thousand, nine hundred eighty-one".