138991000 has 64 divisors (see below), whose sum is σ = 328030560. Its totient is φ = 55120000.

The previous prime is 138990991. The next prime is 138991003. The reversal of 138991000 is 199831.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138991003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 130470 + ... + 131530.

Almost surely, 2^138991000 is an apocalyptic number.

138991000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138991000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (164015280).

138991000 is an abundant number, since it is smaller than the sum of its proper divisors (189039560).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

138991000 is a wasteful number, since it uses less digits than its factorization.

138991000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1213 (or 1199 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 138991000 is about 11789.4444313547. Note that the first 4 decimals coincide. The cubic root of 138991000 is about 517.9989664216.

The spelling of 138991000 in words is "one hundred thirty-eight million, nine hundred ninety-one thousand".