18981437 has 4 divisors (see below), whose sum is σ = 19980480. Its totient is φ = 17982396.

The previous prime is 18981433. The next prime is 18981439. The reversal of 18981437 is 73418981.

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, and also an emirpimes, since its reverse is a distinct semiprime: 73418981 = 29 ⋅2531689.

It is a cyclic number.

It is not a de Polignac number, because 18981437 - 2² = 18981433 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18981394 and 18981403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18981433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 499493 + ... + 499530.

It is an arithmetic number, because the mean of its divisors is an integer number (4995120).

Almost surely, 2^18981437 is an apocalyptic number.

It is an amenable number.

18981437 is a deficient number, since it is larger than the sum of its proper divisors (999043).

18981437 is an equidigital number, since it uses as much as digits as its factorization.

18981437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 999042.

The product of its digits is 48384, while the sum is 41.

The square root of 18981437 is about 4356.7691010656. The cubic root of 18981437 is about 266.7532356091.

The spelling of 18981437 in words is "eighteen million, nine hundred eighty-one thousand, four hundred thirty-seven".