38721618 has 48 divisors (see below), whose sum is σ = 93198240. Its totient is φ = 11911536.

The previous prime is 38721611. The next prime is 38721643. The reversal of 38721618 is 81612783.

38721618 is a `hidden beast` number, since 38 + 7 + 2 + 1 + 618 = 666.

It is an alternating number because its digits alternate between odd and even.

It is not an unprimeable number, because it can be changed into a prime (38721611) 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, 7005 + ... + 11247.

It is an arithmetic number, because the mean of its divisors is an integer number (1941630).

Almost surely, 2^38721618 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 38721618, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46599120).

38721618 is an abundant number, since it is smaller than the sum of its proper divisors (54476622).

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

38721618 is a wasteful number, since it uses less digits than its factorization.

38721618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4280 (or 4261 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 38721618 is about 6222.6696843075. The cubic root of 38721618 is about 338.3123345673.

The spelling of 38721618 in words is "thirty-eight million, seven hundred twenty-one thousand, six hundred eighteen".