138217788 has 36 divisors (see below), whose sum is σ = 356821920. Its totient is φ = 45091776.

The previous prime is 138217757. The next prime is 138217819. The reversal of 138217788 is 887712831.

It is an interprime number because it is at equal distance from previous prime (138217757) and next prime (138217819).

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×138217788² = 38208313839225888, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39153 + ... + 42536.

It is an arithmetic number, because the mean of its divisors is an integer number (9911720).

Almost surely, 2^138217788 is an apocalyptic number.

138217788 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

138217788 is an abundant number, since it is smaller than the sum of its proper divisors (218604132).

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

138217788 is a wasteful number, since it uses less digits than its factorization.

138217788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81746 (or 81741 counting only the distinct ones).

The product of its digits is 150528, while the sum is 45.

The square root of 138217788 is about 11756.6061429309. The cubic root of 138217788 is about 517.0366306617.

It can be divided in two parts, 13821 and 7788, that added together give a square (21609 = 147²).

The spelling of 138217788 in words is "one hundred thirty-eight million, two hundred seventeen thousand, seven hundred eighty-eight".