644362254020669 has 2 divisors, whose sum is σ = 644362254020670. Its totient is φ = 644362254020668.

The previous prime is 644362254020647. The next prime is 644362254020687. The reversal of 644362254020669 is 966020452263446.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 323509505776900 + 320852748243769 = 17986370^2 + 17912363^2 .

It is a cyclic number.

It is not a de Polignac number, because 644362254020669 - 2³² = 644357959053373 is a prime.

It is a super-2 number, since 2×644362254020669² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644362254025669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322181127010334 + 322181127010335.

It is an arithmetic number, because the mean of its divisors is an integer number (322181127010335).

Almost surely, 2^{644362254020669} is an apocalyptic number.

It is an amenable number.

644362254020669 is a deficient number, since it is larger than the sum of its proper divisors (1).

644362254020669 is an equidigital number, since it uses as much as digits as its factorization.

644362254020669 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 89579520, while the sum is 59.

The spelling of 644362254020669 in words is "six hundred forty-four trillion, three hundred sixty-two billion, two hundred fifty-four million, twenty thousand, six hundred sixty-nine".