138721869 has 128 divisors (see below), whose sum is σ = 266649600. Its totient is φ = 69984000.

The previous prime is 138721837. The next prime is 138721871. The reversal of 138721869 is 968127831.

It is not a de Polignac number, because 138721869 - 2⁵ = 138721837 is a prime.

It is a super-2 number, since 2×138721869² = 38487513877706322, which contains 22 as substring.

Its product of digits (145152) is a multiple of the sum of its prime factors (144).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138721879) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2274099 + ... + 2274159.

It is an arithmetic number, because the mean of its divisors is an integer number (2083200).

Almost surely, 2^138721869 is an apocalyptic number.

138721869 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

138721869 is a deficient number, since it is larger than the sum of its proper divisors (127927731).

138721869 is a wasteful number, since it uses less digits than its factorization.

138721869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144 (or 138 counting only the distinct ones).

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

The square root of 138721869 is about 11778.0248344109. The cubic root of 138721869 is about 517.6644132077.

The spelling of 138721869 in words is "one hundred thirty-eight million, seven hundred twenty-one thousand, eight hundred sixty-nine".