18640705 has 4 divisors (see below), whose sum is σ = 22368852. Its totient is φ = 14912560.

The previous prime is 18640693. The next prime is 18640723. The reversal of 18640705 is 50704681.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2903616 + 15737089 = 1704^2 + 3967^2 .

It is not a de Polignac number, because 18640705 - 2¹³ = 18632513 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1864066 + ... + 1864075.

It is an arithmetic number, because the mean of its divisors is an integer number (5592213).

Almost surely, 2^18640705 is an apocalyptic number.

It is an amenable number.

18640705 is a deficient number, since it is larger than the sum of its proper divisors (3728147).

18640705 is an equidigital number, since it uses as much as digits as its factorization.

18640705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3728146.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 18640705 is about 4317.4882744485. The cubic root of 18640705 is about 265.1474437582.

The spelling of 18640705 in words is "eighteen million, six hundred forty thousand, seven hundred five".