638974747 has 2 divisors, whose sum is σ = 638974748. Its totient is φ = 638974746.

The previous prime is 638974723. The next prime is 638974751. The reversal of 638974747 is 747479836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638974747 - 2¹⁹ = 638450459 is a prime.

It is not a weakly prime, because it can be changed into another prime (638971747) 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, 319487373 + 319487374.

It is an arithmetic number, because the mean of its divisors is an integer number (319487374).

Almost surely, 2^638974747 is an apocalyptic number.

638974747 is a deficient number, since it is larger than the sum of its proper divisors (1).

638974747 is an equidigital number, since it uses as much as digits as its factorization.

638974747 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7112448, while the sum is 55.

The square root of 638974747 is about 25277.9498179738. The cubic root of 638974747 is about 861.3134549357.

It can be divided in two parts, 63897 and 4747, that added together give a square (68644 = 262²).

The spelling of 638974747 in words is "six hundred thirty-eight million, nine hundred seventy-four thousand, seven hundred forty-seven".