138878640 has 60 divisors (see below), whose sum is σ = 466403184. Its totient is φ = 37034112.

The previous prime is 138878633. The next prime is 138878647. The reversal of 138878640 is 46878831.

It is an interprime number because it is at equal distance from previous prime (138878633) and next prime (138878647).

It is a tau number, because it is divible by the number of its divisors (60).

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (138878647) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 95724 + ... + 97163.

Almost surely, 2^138878640 is an apocalyptic number.

138878640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

138878640 is an abundant number, since it is smaller than the sum of its proper divisors (327524544).

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

138878640 is a wasteful number, since it uses less digits than its factorization.

138878640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192906 (or 192897 counting only the distinct ones).

The product of its (nonzero) digits is 258048, while the sum is 45.

The square root of 138878640 is about 11784.6781882239. The cubic root of 138878640 is about 517.8593457400.

The spelling of 138878640 in words is "one hundred thirty-eight million, eight hundred seventy-eight thousand, six hundred forty".