1638225947 has 2 divisors, whose sum is σ = 1638225948. Its totient is φ = 1638225946.

The previous prime is 1638225877. The next prime is 1638225973. The reversal of 1638225947 is 7495228361.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1638225947 - 2⁸ = 1638225691 is a prime.

It is not a weakly prime, because it can be changed into another prime (1638221947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819112973 + 819112974.

It is an arithmetic number, because the mean of its divisors is an integer number (819112974).

Almost surely, 2^1638225947 is an apocalyptic number.

1638225947 is a deficient number, since it is larger than the sum of its proper divisors (1).

1638225947 is an equidigital number, since it uses as much as digits as its factorization.

1638225947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 725760, while the sum is 47.

The square root of 1638225947 is about 40475.0039777639. The cubic root of 1638225947 is about 1178.8483322054.

The spelling of 1638225947 in words is "one billion, six hundred thirty-eight million, two hundred twenty-five thousand, nine hundred forty-seven".