28777390321 has 3 divisors (see below), whose sum is σ = 28777559961. Its totient is φ = 28777220682.

The previous prime is 28777390289. The next prime is 28777390333. The reversal of 28777390321 is 12309377782.

It is a happy number.

The square root of 28777390321 is 169639.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 28777390321 - 2⁵ = 28777390289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28777390351) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 84820 + ... + 254458.

It is an arithmetic number, because the mean of its divisors is an integer number (9592519987).

Almost surely, 2^28777390321 is an apocalyptic number.

28777390321 is the 169639-th square number.

28777390321 is the 84820-th centered octagonal number.

It is an amenable number.

28777390321 is a deficient number, since it is larger than the sum of its proper divisors (169640).

28777390321 is an frugal number, since it uses more digits than its factorization.

28777390321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339278 (or 169639 counting only the distinct ones).

The product of its (nonzero) digits is 889056, while the sum is 49.

Multiplying 28777390321 by its sum of digits (49), we get a square (1410092125729 = 1187473²).

The spelling of 28777390321 in words is "twenty-eight billion, seven hundred seventy-seven million, three hundred ninety thousand, three hundred twenty-one".