638540479 has 2 divisors, whose sum is σ = 638540480. Its totient is φ = 638540478.

The previous prime is 638540453. The next prime is 638540491. The reversal of 638540479 is 974045836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638540479 - 2²⁵ = 604986047 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638540579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319270239 + 319270240.

It is an arithmetic number, because the mean of its divisors is an integer number (319270240).

Almost surely, 2^638540479 is an apocalyptic number.

638540479 is a deficient number, since it is larger than the sum of its proper divisors (1).

638540479 is an equidigital number, since it uses as much as digits as its factorization.

638540479 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 725760, while the sum is 46.

The square root of 638540479 is about 25269.3584999699. The cubic root of 638540479 is about 861.1182851777.

It can be divided in two parts, 6385 and 40479, that added together give a palindrome (46864).

The spelling of 638540479 in words is "six hundred thirty-eight million, five hundred forty thousand, four hundred seventy-nine".