19780165 has 8 divisors (see below), whose sum is σ = 24125688. Its totient is φ = 15564480.

The previous prime is 19780157. The next prime is 19780169. The reversal of 19780165 is 56108791.

It can be written as a sum of positive squares in 4 ways, for example, as 543169 + 19236996 = 737^2 + 4386^2 .

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

It is not a de Polignac number, because 19780165 - 2³ = 19780157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19780169) 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, 32122 + ... + 32731.

It is an arithmetic number, because the mean of its divisors is an integer number (3015711).

Almost surely, 2^19780165 is an apocalyptic number.

It is an amenable number.

19780165 is a deficient number, since it is larger than the sum of its proper divisors (4345523).

19780165 is an equidigital number, since it uses as much as digits as its factorization.

19780165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64919.

The product of its (nonzero) digits is 15120, while the sum is 37.

The square root of 19780165 is about 4447.4897414159. The cubic root of 19780165 is about 270.4435553372.

The spelling of 19780165 in words is "nineteen million, seven hundred eighty thousand, one hundred sixty-five".