18820781 has 8 divisors (see below), whose sum is σ = 21622464. Its totient is φ = 16047360.

The previous prime is 18820771. The next prime is 18820793. The reversal of 18820781 is 18702881.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-18820781 is a prime.

It is a super-2 number, since 2×18820781² = 708443594899922, 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 (18820771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5615 + ... + 8316.

It is an arithmetic number, because the mean of its divisors is an integer number (2702808).

Almost surely, 2^18820781 is an apocalyptic number.

It is an amenable number.

18820781 is a deficient number, since it is larger than the sum of its proper divisors (2801683).

18820781 is a wasteful number, since it uses less digits than its factorization.

18820781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14131.

The product of its (nonzero) digits is 7168, while the sum is 35.

The square root of 18820781 is about 4338.2924060049. The cubic root of 18820781 is about 265.9985160186.

The spelling of 18820781 in words is "eighteen million, eight hundred twenty thousand, seven hundred eighty-one".