18890781 has 16 divisors (see below), whose sum is σ = 31000704. Its totient is φ = 9964224.

The previous prime is 18890779. The next prime is 18890783. The reversal of 18890781 is 18709881.

It is an interprime number because it is at equal distance from previous prime (18890779) and next prime (18890783).

It is not a de Polignac number, because 18890781 - 2¹ = 18890779 is a prime.

It is a super-2 number, since 2×18890781² = 713723213579922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18890783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34326 + ... + 34871.

It is an arithmetic number, because the mean of its divisors is an integer number (1937544).

Almost surely, 2^18890781 is an apocalyptic number.

It is an amenable number.

18890781 is a deficient number, since it is larger than the sum of its proper divisors (12109923).

18890781 is a wasteful number, since it uses less digits than its factorization.

18890781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69220.

The product of its (nonzero) digits is 32256, while the sum is 42.

The square root of 18890781 is about 4346.3526087974. The cubic root of 18890781 is about 266.3278834949.

The spelling of 18890781 in words is "eighteen million, eight hundred ninety thousand, seven hundred eighty-one".