1638477649 has 2 divisors, whose sum is σ = 1638477650. Its totient is φ = 1638477648.

The previous prime is 1638477569. The next prime is 1638477671. The reversal of 1638477649 is 9467748361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1181159424 + 457318225 = 34368^2 + 21385^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1638477649 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1638477649.

It is not a weakly prime, because it can be changed into another prime (1638477679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819238824 + 819238825.

It is an arithmetic number, because the mean of its divisors is an integer number (819238825).

Almost surely, 2^1638477649 is an apocalyptic number.

It is an amenable number.

1638477649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638477649 is an equidigital number, since it uses as much as digits as its factorization.

1638477649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6096384, while the sum is 55.

The square root of 1638477649 is about 40478.1132094864. The cubic root of 1638477649 is about 1178.9087030573.

The spelling of 1638477649 in words is "one billion, six hundred thirty-eight million, four hundred seventy-seven thousand, six hundred forty-nine".