63721638 has 48 divisors (see below), whose sum is σ = 145173600. Its totient is φ = 20161152.

The previous prime is 63721589. The next prime is 63721639. The reversal of 63721638 is 83612736.

It is a happy number.

63721638 is a `hidden beast` number, since 637 + 2 + 16 + 3 + 8 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63721639) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 61170 + ... + 62202.

It is an arithmetic number, because the mean of its divisors is an integer number (3024450).

Almost surely, 2^63721638 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 63721638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72586800).

63721638 is an abundant number, since it is smaller than the sum of its proper divisors (81451962).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

63721638 is a wasteful number, since it uses less digits than its factorization.

63721638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1213 (or 1210 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 63721638 is about 7982.5834164135. The cubic root of 63721638 is about 399.4192363587.

The spelling of 63721638 in words is "sixty-three million, seven hundred twenty-one thousand, six hundred thirty-eight".