28709574721 has 9 divisors (see below), whose sum is σ = 30500774499. Its totient is φ = 27018065184.

The previous prime is 28709574713. The next prime is 28709574737. The reversal of 28709574721 is 12747590782.

The square root of 28709574721 is 169439.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 22351745025 + 6357829696 = 149505^2 + 79736^2 .

It is not a de Polignac number, because 28709574721 - 2³ = 28709574713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28709574701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2875480 + ... + 2885446.

Almost surely, 2^28709574721 is an apocalyptic number.

28709574721 is the 169439-th square number.

28709574721 is the 84720-th centered octagonal number.

It is an amenable number.

28709574721 is a deficient number, since it is larger than the sum of its proper divisors (1791199778).

28709574721 is an frugal number, since it uses more digits than its factorization.

28709574721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19968 (or 9984 counting only the distinct ones).

The product of its (nonzero) digits is 1975680, while the sum is 52.

The spelling of 28709574721 in words is "twenty-eight billion, seven hundred nine million, five hundred seventy-four thousand, seven hundred twenty-one".