1640399 has 2 divisors, whose sum is σ = 1640400. Its totient is φ = 1640398.

The previous prime is 1640393. The next prime is 1640423. The reversal of 1640399 is 9930461.

It is a weak prime.

It is an emirp because it is prime and its reverse (9930461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1640399 - 2¹² = 1636303 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1640393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820199 + 820200.

It is an arithmetic number, because the mean of its divisors is an integer number (820200).

2^1640399 is an apocalyptic number.

1640399 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640399 is an equidigital number, since it uses as much as digits as its factorization.

1640399 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 1640399 is about 1280.7806213400. The cubic root of 1640399 is about 117.9369336461.

The spelling of 1640399 in words is "one million, six hundred forty thousand, three hundred ninety-nine".