72157728 has 24 divisors (see below), whose sum is σ = 189414288. Its totient is φ = 24052544.

The previous prime is 72157721. The next prime is 72157747. The reversal of 72157728 is 82775127.

It is a tau number, because it is divible by the number of its divisors (24).

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (72157721) 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, 375726 + ... + 375917.

It is an arithmetic number, because the mean of its divisors is an integer number (7892262).

Almost surely, 2^72157728 is an apocalyptic number.

It is an amenable number.

72157728 is an abundant number, since it is smaller than the sum of its proper divisors (117256560).

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

72157728 is a wasteful number, since it uses less digits than its factorization.

72157728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 751656 (or 751648 counting only the distinct ones).

The product of its digits is 54880, while the sum is 39.

The square root of 72157728 is about 8494.5705012084. The cubic root of 72157728 is about 416.3203277360.

The spelling of 72157728 in words is "seventy-two million, one hundred fifty-seven thousand, seven hundred twenty-eight".