42139939 has 2 divisors, whose sum is σ = 42139940. Its totient is φ = 42139938.

The previous prime is 42139931. The next prime is 42139973. The reversal of 42139939 is 93993124.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 42139939 - 2³ = 42139931 is a prime.

It is not a weakly prime, because it can be changed into another prime (42139931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21069969 + 21069970.

It is an arithmetic number, because the mean of its divisors is an integer number (21069970).

Almost surely, 2^42139939 is an apocalyptic number.

42139939 is a deficient number, since it is larger than the sum of its proper divisors (1).

42139939 is an equidigital number, since it uses as much as digits as its factorization.

42139939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52488, while the sum is 40.

The square root of 42139939 is about 6491.5282484173. The cubic root of 42139939 is about 347.9882934143.

The spelling of 42139939 in words is "forty-two million, one hundred thirty-nine thousand, nine hundred thirty-nine".