1640699 has 4 divisors (see below), whose sum is σ = 1644720. Its totient is φ = 1636680.

The previous prime is 1640689. The next prime is 1640701. The reversal of 1640699 is 9960461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9960461 = 7 ⋅1422923.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1640699 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1640609) 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 3 ways as a sum of consecutive naturals, for example, 1319 + ... + 2240.

It is an arithmetic number, because the mean of its divisors is an integer number (411180).

2^1640699 is an apocalyptic number.

1640699 is a deficient number, since it is larger than the sum of its proper divisors (4021).

1640699 is an equidigital number, since it uses as much as digits as its factorization.

1640699 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4020.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 1640699 is about 1280.8977320614. The cubic root of 1640699 is about 117.9441227351.

It can be divided in two parts, 164069 and 9, that multiplied together give a triangular number (1476621 = T₁₇₁₈).

The spelling of 1640699 in words is "one million, six hundred forty thousand, six hundred ninety-nine".