15773721728 has 72 divisors (see below), whose sum is σ = 33432626955. Its totient is φ = 7411560448.

The previous prime is 15773721727. The next prime is 15773721757. The reversal of 15773721728 is 82712737751.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 5 ways, for example, as 8098560064 + 7675161664 = 89992^2 + 87608^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=88808.

Its product of digits (1152480) is a multiple of the sum of its prime divisors (672).

It is not an unprimeable number, because it can be changed into a prime (15773721727) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 24155450 + ... + 24156102.

Almost surely, 2^15773721728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15773721728

15773721728 is an abundant number, since it is smaller than the sum of its proper divisors (17658905227).

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

15773721728 is an frugal number, since it uses more digits than its factorization.

15773721728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1354 (or 672 counting only the distinct ones).

The product of its digits is 1152480, while the sum is 50.

Multiplying 15773721728 by its sum of digits (50), we get a square (788686086400 = 888080²).

The spelling of 15773721728 in words is "fifteen billion, seven hundred seventy-three million, seven hundred twenty-one thousand, seven hundred twenty-eight".