28221777 has 14 divisors (see below), whose sum is σ = 42314402. Its totient is φ = 18814032.

The previous prime is 28221769. The next prime is 28221793. The reversal of 28221777 is 77712282.

It can be written as a sum of positive squares in only one way, i.e., 26873856 + 1347921 = 5184^2 + 1161^2 .

It is not a de Polignac number, because 28221777 - 2³ = 28221769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28221737) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 18628 + ... + 20085.

Almost surely, 2^28221777 is an apocalyptic number.

28221777 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

28221777 is a deficient number, since it is larger than the sum of its proper divisors (14092625).

28221777 is an frugal number, since it uses more digits than its factorization.

28221777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38731 (or 38716 counting only the distinct ones).

The product of its digits is 21952, while the sum is 36.

The square root of 28221777 is about 5312.4172464143. The cubic root of 28221777 is about 304.4585106907.

The spelling of 28221777 in words is "twenty-eight million, two hundred twenty-one thousand, seven hundred seventy-seven".