644774487787 has 2 divisors, whose sum is σ = 644774487788. Its totient is φ = 644774487786.

The previous prime is 644774487761. The next prime is 644774487803. The reversal of 644774487787 is 787784477446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644774487787 - 2⁷ = 644774487659 is a prime.

It is not a weakly prime, because it can be changed into another prime (644774487737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322387243893 + 322387243894.

It is an arithmetic number, because the mean of its divisors is an integer number (322387243894).

Almost surely, 2^644774487787 is an apocalyptic number.

644774487787 is a deficient number, since it is larger than the sum of its proper divisors (1).

644774487787 is an equidigital number, since it uses as much as digits as its factorization.

644774487787 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1652195328, while the sum is 73.

The spelling of 644774487787 in words is "six hundred forty-four billion, seven hundred seventy-four million, four hundred eighty-seven thousand, seven hundred eighty-seven".