635978209649 has 2 divisors, whose sum is σ = 635978209650. Its totient is φ = 635978209648.

The previous prime is 635978209613. The next prime is 635978209663. The reversal of 635978209649 is 946902879536.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 598828345600 + 37149864049 = 773840^2 + 192743^2 .

It is a cyclic number.

It is not a de Polignac number, because 635978209649 - 2¹² = 635978205553 is a prime.

It is not a weakly prime, because it can be changed into another prime (635978209849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 317989104824 + 317989104825.

It is an arithmetic number, because the mean of its divisors is an integer number (317989104825).

Almost surely, 2^635978209649 is an apocalyptic number.

It is an amenable number.

635978209649 is a deficient number, since it is larger than the sum of its proper divisors (1).

635978209649 is an equidigital number, since it uses as much as digits as its factorization.

635978209649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 176359680, while the sum is 68.

The spelling of 635978209649 in words is "six hundred thirty-five billion, nine hundred seventy-eight million, two hundred nine thousand, six hundred forty-nine".