28138791123 has 40 divisors (see below), whose sum is σ = 44264800800. Its totient is φ = 17778828672.

The previous prime is 28138791097. The next prime is 28138791151. The reversal of 28138791123 is 32119783182.

It is not a de Polignac number, because 28138791123 - 2⁹ = 28138790611 is a prime.

It is a super-2 number, since 2×28138791123² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28138791823) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 133783 + ... + 272351.

It is an arithmetic number, because the mean of its divisors is an integer number (1106620020).

Almost surely, 2^28138791123 is an apocalyptic number.

28138791123 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

28138791123 is a deficient number, since it is larger than the sum of its proper divisors (16126009677).

28138791123 is a wasteful number, since it uses less digits than its factorization.

28138791123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138713 (or 138704 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The spelling of 28138791123 in words is "twenty-eight billion, one hundred thirty-eight million, seven hundred ninety-one thousand, one hundred twenty-three".