638120137 has 2 divisors, whose sum is σ = 638120138. Its totient is φ = 638120136.

The previous prime is 638120101. The next prime is 638120173. The reversal of 638120137 is 731021836.

Together with next prime (638120173) it forms an Ormiston pair, because they use the same digits, order apart.

It is a balanced prime because it is at equal distance from previous prime (638120101) and next prime (638120173).

It can be written as a sum of positive squares in only one way, i.e., 598731961 + 39388176 = 24469^2 + 6276^2 .

It is a cyclic number.

It is not a de Polignac number, because 638120137 - 2²⁷ = 503902409 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 638120099 and 638120108.

It is not a weakly prime, because it can be changed into another prime (638120237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319060068 + 319060069.

It is an arithmetic number, because the mean of its divisors is an integer number (319060069).

Almost surely, 2^638120137 is an apocalyptic number.

It is an amenable number.

638120137 is a deficient number, since it is larger than the sum of its proper divisors (1).

638120137 is an equidigital number, since it uses as much as digits as its factorization.

638120137 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6048, while the sum is 31.

The square root of 638120137 is about 25261.0399033769. The cubic root of 638120137 is about 860.9292897793.

The spelling of 638120137 in words is "six hundred thirty-eight million, one hundred twenty thousand, one hundred thirty-seven".