63939981 has 16 divisors (see below), whose sum is σ = 97584768. Its totient is φ = 36480000.

The previous prime is 63939979. The next prime is 63939989. The reversal of 63939981 is 18993936.

It is a happy number.

It is not a de Polignac number, because 63939981 - 2¹ = 63939979 is a prime.

It is a super-2 number, since 2×63939981² = 8176642340560722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 63939981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63939989) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13981 + ... + 17981.

It is an arithmetic number, because the mean of its divisors is an integer number (6099048).

Almost surely, 2^63939981 is an apocalyptic number.

It is an amenable number.

63939981 is a deficient number, since it is larger than the sum of its proper divisors (33644787).

63939981 is a wasteful number, since it uses less digits than its factorization.

63939981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4772.

The product of its digits is 314928, while the sum is 48.

The square root of 63939981 is about 7996.2479326244. The cubic root of 63939981 is about 399.8749213090.

The spelling of 63939981 in words is "sixty-three million, nine hundred thirty-nine thousand, nine hundred eighty-one".