19928781 has 16 divisors (see below), whose sum is σ = 29931520. Its totient is φ = 13102560.

The previous prime is 19928773. The next prime is 19928789. The reversal of 19928781 is 18782991.

It is an interprime number because it is at equal distance from previous prime (19928773) and next prime (19928789).

It is not a de Polignac number, because 19928781 - 2³ = 19928773 is a prime.

It is a super-2 number, since 2×19928781² = 794312624291922, 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 (19928789) 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 15 ways as a sum of consecutive naturals, for example, 3085 + ... + 7026.

It is an arithmetic number, because the mean of its divisors is an integer number (1870720).

Almost surely, 2^19928781 is an apocalyptic number.

It is an amenable number.

19928781 is a deficient number, since it is larger than the sum of its proper divisors (10002739).

19928781 is a wasteful number, since it uses less digits than its factorization.

19928781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10193 (or 10187 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The square root of 19928781 is about 4464.1663275465. The cubic root of 19928781 is about 271.1191816118.

The spelling of 19928781 in words is "nineteen million, nine hundred twenty-eight thousand, seven hundred eighty-one".