138617820 has 72 divisors (see below), whose sum is σ = 458705520. Its totient is φ = 33603840.

The previous prime is 138617819. The next prime is 138617821. The reversal of 138617820 is 28716831.

138617820 is a `hidden beast` number, since 1 + 38 + 617 + 8 + 2 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (138617819) and next prime (138617821).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138617821) 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, 33025 + ... + 36984.

It is an arithmetic number, because the mean of its divisors is an integer number (6370910).

Almost surely, 2^138617820 is an apocalyptic number.

138617820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

138617820 is an abundant number, since it is smaller than the sum of its proper divisors (320087700).

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

138617820 is a wasteful number, since it uses less digits than its factorization.

138617820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70035 (or 70030 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 138617820 is about 11773.6069239634. The cubic root of 138617820 is about 517.5349552808.

The spelling of 138617820 in words is "one hundred thirty-eight million, six hundred seventeen thousand, eight hundred twenty".