28637681 has 4 divisors (see below), whose sum is σ = 29030052. Its totient is φ = 28245312.

The previous prime is 28637671. The next prime is 28637689. The reversal of 28637681 is 18673682.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5837056 + 22800625 = 2416^2 + 4775^2 .

It is a cyclic number.

It is not a de Polignac number, because 28637681 - 2¹⁴ = 28621297 is a prime.

It is a super-2 number, since 2×28637681² = 1640233546115522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28637689) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 196076 + ... + 196221.

It is an arithmetic number, because the mean of its divisors is an integer number (7257513).

Almost surely, 2^28637681 is an apocalyptic number.

It is an amenable number.

28637681 is a deficient number, since it is larger than the sum of its proper divisors (392371).

28637681 is an equidigital number, since it uses as much as digits as its factorization.

28637681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 392370.

The product of its digits is 96768, while the sum is 41.

The square root of 28637681 is about 5351.4185969703. The cubic root of 28637681 is about 305.9468238865.

The spelling of 28637681 in words is "twenty-eight million, six hundred thirty-seven thousand, six hundred eighty-one".