27981581 has 4 divisors (see below), whose sum is σ = 27996192. Its totient is φ = 27966972.

The previous prime is 27981571. The next prime is 27981587. The reversal of 27981581 is 18518972.

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 a de Polignac number, because none of the positive numbers 2^k-27981581 is a prime.

It is a super-2 number, since 2×27981581² = 1565937750519122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27981587) 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, 3905 + ... + 8438.

It is an arithmetic number, because the mean of its divisors is an integer number (6999048).

Almost surely, 2^27981581 is an apocalyptic number.

It is an amenable number.

27981581 is a deficient number, since it is larger than the sum of its proper divisors (14611).

27981581 is a wasteful number, since it uses less digits than its factorization.

27981581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14610.

The product of its digits is 40320, while the sum is 41.

The square root of 27981581 is about 5289.7619039046. The cubic root of 27981581 is about 303.5922981388.

The spelling of 27981581 in words is "twenty-seven million, nine hundred eighty-one thousand, five hundred eighty-one".