28369781 has 6 divisors (see below), whose sum is σ = 31183446. Its totient is φ = 25790600.

The previous prime is 28369763. The next prime is 28369799. The reversal of 28369781 is 18796382.

It is an interprime number because it is at equal distance from previous prime (28369763) and next prime (28369799).

It can be written as a sum of positive squares in only one way, i.e., 27300625 + 1069156 = 5225^2 + 1034^2 .

It is not a de Polignac number, because 28369781 - 2¹⁴ = 28353397 is a prime.

It is a super-2 number, since 2×28369781² = 1609688947975922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28369711) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 117110 + ... + 117351.

It is an arithmetic number, because the mean of its divisors is an integer number (5197241).

Almost surely, 2^28369781 is an apocalyptic number.

It is an amenable number.

28369781 is a deficient number, since it is larger than the sum of its proper divisors (2813665).

28369781 is a wasteful number, since it uses less digits than its factorization.

28369781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234483 (or 234472 counting only the distinct ones).

The product of its digits is 145152, while the sum is 44.

The square root of 28369781 is about 5326.3290360247. The cubic root of 28369781 is about 304.9898088506.

The spelling of 28369781 in words is "twenty-eight million, three hundred sixty-nine thousand, seven hundred eighty-one".