1640671787 has 2 divisors, whose sum is σ = 1640671788. Its totient is φ = 1640671786.

The previous prime is 1640671777. The next prime is 1640671789. The reversal of 1640671787 is 7871760461.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1640671787 - 2⁸ = 1640671531 is a prime.

Together with 1640671789, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1640671789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820335893 + 820335894.

It is an arithmetic number, because the mean of its divisors is an integer number (820335894).

Almost surely, 2^1640671787 is an apocalyptic number.

1640671787 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640671787 is an equidigital number, since it uses as much as digits as its factorization.

1640671787 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 395136, while the sum is 47.

The square root of 1640671787 is about 40505.2069121983. The cubic root of 1640671787 is about 1179.4347064899.

The spelling of 1640671787 in words is "one billion, six hundred forty million, six hundred seventy-one thousand, seven hundred eighty-seven".