1660639 has 4 divisors (see below), whose sum is σ = 1714240. Its totient is φ = 1607040.

The previous prime is 1660609. The next prime is 1660661. The reversal of 1660639 is 9360661.

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

It is a de Polignac number, because none of the positive numbers 2^k-1660639 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 53569 = 1660639 / (1 + 6 + 6 + 0 + 6 + 3 + 9).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1660639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1660609) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26754 + ... + 26815.

It is an arithmetic number, because the mean of its divisors is an integer number (428560).

2^1660639 is an apocalyptic number.

1660639 is a deficient number, since it is larger than the sum of its proper divisors (53601).

1660639 is an equidigital number, since it uses as much as digits as its factorization.

1660639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53600.

The product of its (nonzero) digits is 5832, while the sum is 31.

The square root of 1660639 is about 1288.6578289057. The cubic root of 1660639 is about 118.4200057122.

The spelling of 1660639 in words is "one million, six hundred sixty thousand, six hundred thirty-nine".