63981913 has 4 divisors (see below), whose sum is σ = 64261540. Its totient is φ = 63702288.

The previous prime is 63981889. The next prime is 63981937. The reversal of 63981913 is 31918936.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (63981889) and next prime (63981937).

It can be written as a sum of positive squares in 2 ways, for example, as 34257609 + 29724304 = 5853^2 + 5452^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-63981913 is a prime.

It is a super-2 number, since 2×63981913² = 8187370382279138, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (63981943) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139470 + ... + 139927.

It is an arithmetic number, because the mean of its divisors is an integer number (16065385).

Almost surely, 2^63981913 is an apocalyptic number.

It is an amenable number.

63981913 is a deficient number, since it is larger than the sum of its proper divisors (279627).

63981913 is a wasteful number, since it uses less digits than its factorization.

63981913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279626.

The product of its digits is 34992, while the sum is 40.

The square root of 63981913 is about 7998.8694826207. The cubic root of 63981913 is about 399.9623151998.

The spelling of 63981913 in words is "sixty-three million, nine hundred eighty-one thousand, nine hundred thirteen".