1638749407 has 2 divisors, whose sum is σ = 1638749408. Its totient is φ = 1638749406.

The previous prime is 1638749363. The next prime is 1638749417. The reversal of 1638749407 is 7049478361.

It is a strong prime.

It is an emirp because it is prime and its reverse (7049478361) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1638749407 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1638749417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819374703 + 819374704.

It is an arithmetic number, because the mean of its divisors is an integer number (819374704).

Almost surely, 2^1638749407 is an apocalyptic number.

1638749407 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638749407 is an equidigital number, since it uses as much as digits as its factorization.

1638749407 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1016064, while the sum is 49.

The square root of 1638749407 is about 40481.4699214344. The cubic root of 1638749407 is about 1178.9738774099.

The spelling of 1638749407 in words is "one billion, six hundred thirty-eight million, seven hundred forty-nine thousand, four hundred seven".