15500138 has 4 divisors (see below), whose sum is σ = 23250210. Its totient is φ = 7750068.

The previous prime is 15500131. The next prime is 15500153. The reversal of 15500138 is 83100551.

15500138 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83100551 = 3823 ⋅21737.

It can be written as a sum of positive squares in only one way, i.e., 15499969 + 169 = 3937^2 + 13^2 .

It is not an unprimeable number, because it can be changed into a prime (15500131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3875033 + ... + 3875036.

Almost surely, 2^15500138 is an apocalyptic number.

15500138 is a deficient number, since it is larger than the sum of its proper divisors (7750072).

15500138 is an equidigital number, since it uses as much as digits as its factorization.

15500138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7750071.

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 15500138 is about 3937.0214629844. The cubic root of 15500138 is about 249.3322875614.

Adding to 15500138 its reverse (83100551), we get a palindrome (98600689).

The spelling of 15500138 in words is "fifteen million, five hundred thousand, one hundred thirty-eight".