138624491 has 4 divisors (see below), whose sum is σ = 139475112. Its totient is φ = 137773872.

The previous prime is 138624487. The next prime is 138624509. The reversal of 138624491 is 194426831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 194426831 = 67 ⋅2901893.

It is a cyclic number.

It is not a de Polignac number, because 138624491 - 2² = 138624487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138624481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 425066 + ... + 425391.

It is an arithmetic number, because the mean of its divisors is an integer number (34868778).

Almost surely, 2^138624491 is an apocalyptic number.

138624491 is a deficient number, since it is larger than the sum of its proper divisors (850621).

138624491 is an equidigital number, since it uses as much as digits as its factorization.

138624491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 850620.

The product of its digits is 41472, while the sum is 38.

The square root of 138624491 is about 11773.8902237111. The cubic root of 138624491 is about 517.5432572925.

The spelling of 138624491 in words is "one hundred thirty-eight million, six hundred twenty-four thousand, four hundred ninety-one".