27857981 has 4 divisors (see below), whose sum is σ = 28450752. Its totient is φ = 27265212.

The previous prime is 27857969. The next prime is 27857989. The reversal of 27857981 is 18975872.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 27857981 - 2¹⁰ = 27856957 is a prime.

It is a super-2 number, since 2×27857981² = 1552134210792722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (47), and also a Moran number because the ratio is a prime number: 592723 = 27857981 / (2 + 7 + 8 + 5 + 7 + 9 + 8 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27857989) 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, 296315 + ... + 296408.

It is an arithmetic number, because the mean of its divisors is an integer number (7112688).

Almost surely, 2^27857981 is an apocalyptic number.

It is an amenable number.

27857981 is a deficient number, since it is larger than the sum of its proper divisors (592771).

27857981 is an equidigital number, since it uses as much as digits as its factorization.

27857981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 592770.

The product of its digits is 282240, while the sum is 47.

The square root of 27857981 is about 5278.0660283858. The cubic root of 27857981 is about 303.1446299117.

The spelling of 27857981 in words is "twenty-seven million, eight hundred fifty-seven thousand, nine hundred eighty-one".