138649236 has 72 divisors (see below), whose sum is σ = 365010912. Its totient is φ = 40622400.

The previous prime is 138649211. The next prime is 138649237. The reversal of 138649236 is 632946831.

It is a super-2 number, since 2×138649236² = 38447221286767392, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138649237) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 126306 + ... + 127398.

It is an arithmetic number, because the mean of its divisors is an integer number (5069596).

Almost surely, 2^138649236 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138649236, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (182505456).

138649236 is an abundant number, since it is smaller than the sum of its proper divisors (226361676).

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

138649236 is a wasteful number, since it uses less digits than its factorization.

138649236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1173 (or 1140 counting only the distinct ones).

The product of its digits is 186624, while the sum is 42.

The square root of 138649236 is about 11774.9410189606. The cubic root of 138649236 is about 517.5740499417.

The spelling of 138649236 in words is "one hundred thirty-eight million, six hundred forty-nine thousand, two hundred thirty-six".