1636399861 has 2 divisors, whose sum is σ = 1636399862. Its totient is φ = 1636399860.

The previous prime is 1636399859. The next prime is 1636399927. The reversal of 1636399861 is 1689936361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1561040100 + 75359761 = 39510^2 + 8681^2 .

It is a cyclic number.

It is not a de Polignac number, because 1636399861 - 2¹ = 1636399859 is a prime.

Together with 1636399859, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 1636399799 and 1636399808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1636399841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 818199930 + 818199931.

It is an arithmetic number, because the mean of its divisors is an integer number (818199931).

Almost surely, 2^1636399861 is an apocalyptic number.

It is an amenable number.

1636399861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1636399861 is an equidigital number, since it uses as much as digits as its factorization.

1636399861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1259712, while the sum is 52.

The square root of 1636399861 is about 40452.4394938056. The cubic root of 1636399861 is about 1178.4101592783.

The spelling of 1636399861 in words is "one billion, six hundred thirty-six million, three hundred ninety-nine thousand, eight hundred sixty-one".